Making A Giant Egg

 

Completed egg shells

Completed fibreglass shells painted in shellac ready for finishing

The first step in making a giant egg is to make a giant egg – so a mould can be made.

Depending on the size of the egg you want to make will dictate how you go about making the egg form. Since the egg we needed to make was about 60cm tall it was decided to carve it from a block of polystyrene. Since the egg shape is symmetrical it is best to turn it on a lathe.

Preparing polystyrene block for turning

Preparing polystyrene block for turning

The polystyrene has to have plywood boards glued to both ends so a lathe faceplate and tailstock centre can be attached so it can be turned on the lathe.

The corners of the block are then cut off at 45 degrees to make turning a bit easier on the polystyrene. If this is not done it is likely large chunks will break off when the lathe chisel is applied to the turning block.

It is very, very messy turning polystyrene on a lathe so ensure the work area is covered with something to collect the shavings and clean up regularly as you work. This will minimise the polystyrene getting into every nook and cranny of your workshop.

Polystyrene mounted on the lathe ready for turning

Polystyrene mounted on the lathe ready for turning

Basic shape completed on the lathe

Basic shape completed on the lathe

Completed polystyrene egg

Completed polystyrene egg

The polystyrene is removed from the lathe and the two ends trimmed. Sandpaper is used to smooth both ends until their radius makes a smooth transition around the egg shape. It is important to get the shape exactly right with no obvious flat spots or sudden changes in the radius.

To support the egg while making the mould a box was built to put the egg form into so the middle flange can be made with plasticine. Once that has been done it is given a coat of PVA mould release in preparation for fibreglassing.

Ply box for making the top half of the mould.

Ply box for making the top half of the mould.

Flange finished around egg

Flange finished around egg and mould release applied

After the top half has been fibreglassed a timber support is fibreglassed on the mould so it sits horizontal when put on its side. The egg with the first half of the mould attached is removed from the support box and turned upside down to expose the underside of the egg form. This is cleaned up, PVA mould release applied and the second half is coated with fibreglass as described in previous mould making posts.

After polishing the inside of the mould halves with wax fibreglass casts are taken and trimmed to the flange line around the mould on both halves.

The two completed fibreglass mould halves

The two completed fibreglass mould halves

Fibreglass casts for egg ready for joining

Fibreglass casts for egg ready for joining

To ensure that both halves of the egg are joined together securely they need to be fibreglassed along the inside centre seam of the egg. To do this an access panel is cut in one half that is big enough to get your hand inside the egg shell. Blocks of wood are attached to the inside of the shell around where the access panel will be cut. This allows for easy re-installation of the panel section after the work has been done.

You can see the alignment blocks in the photo below with the access panel removed.

Cutting out an access panel in one half

Cutting out an access panel in one half

Access panel removed

Access panel removed so halves can be fibreglassed together

The two halves are taped together with mylar tape to keep them aligned. They are then fibreglassed on the inside along the centre seam. Once this has been done the access panel can be glued back into position and all gaps around the panel opening and the centre egg seam can be filled with polyester filler.

After sanding smooth the fibreglass is given a primer coat of de-waxed shellac.

Halves taped in position

Halves taped in position for fibreglassing from the inside

Access panel glued back in position

Access panel glued back in position and gaps filled and sanded

The completed eggs can be seen in this post.

Making a Giant Heart

Completed giant fibreglass heart

Completed giant 3D fibreglass heart

The making of a giant 3D heart for the recent Wayside Chapel winged heart project was a great exercise in how to sculpt large objects for armatures to make large fibreglass moulds. The heart had to be made as quickly and cheaply as possible so some shortcuts were made that had both positive and negative consequences.

Instead of making a two piece mould it was decided to make a perfectly symmetrical half mould so both front and rear sections could be cast from the same mould. This was achieved by first drawing half a heart on a piece of plywood. A second piece of plywood was fastened under the first and then both pieces were cut as one on a bandsaw. After sanding the the edges smooth the plywood *sandwich* was split and fastened together, side by side, making a perfectly symmetrical heart shape.

Heart outline in ply

A symmetrical outline of the heart was made from ply and fastened to support table

making armature with ply strips

Building up the heart profile using templates and ply strips

Heart shape in ply strips

Rough heart shape defined by ply strips

Hessian covering over ply

Ply framework covered with hessian

Plaster applied over hessian

Casting plaster was applied over the hessian covering to make it rigid.

second layer of plaster and hessian applied

A second layer of casting plaster and hessian is applied over form work

To smooth the heart shape a thick layer of Gyprock top coat filler was applied using a spatula taking care to make the layer as smooth as possible.

Applying Gyprock

Applying the Gyprock top coat filler over the plaster form. It was carefully filled out to match the heart outline defined by the base ply template.

Smoothing the form

Form ready for smoothing after the Gyprock dried

In the rush to get the mould made I decided to save time by not making the heart form super smooth before applying gelcoat and matting. Instead I would apply a double thickness of gelcoat when making the mould and then sand any irregularities from the mould directly. A quick coating of wax mould release was applied before applying the gelcoat and fibreglass matting over the heart form. This was a big mistake. The wax soaked into the not quite dry Gyprock allowing the gelcoat to stick firmly to the heart form making its easy removal impossible.

Mould completion

With the fibreglassing completed the mould was ready to be removed from the form but it would not budge.

Removing the heart form

The mould was firmly stuck to the heart form. Weighing in at over 100kg the mould had to be lifted from the work table so the form could be cut out from underneath the mould

Removing formwork

Once the bottom of the mould was exposed the timber formwork could be dug out

Plaster removal

Removing the plaster and hessian reinforcement

Once the ply form work and hessian had been removed there was still a thick layer of plaster and Gyprock stuck firmly to the fibreglass. The only way to remove it was to use a hammer and chisel. The chisel had its corners rounded and the cutting edge dulled to minimise the inevitable damage that would be done to the mould interior surface.

Removing the plaster and Gyprock

After 4 hours work only half the mould had been cleaned.

More plaster removal

About 8 hours later the last of the plaster and Gyprock was removed from the fibreglass surface

Cleaning mould

Wet’n’dry was used to sand the irregularities and scratches from the mould inside surface

Waxed mould ready for use

The mould after being cleaned and waxed ready to have a cast taken

Red gelcoat in mould

First layer of gelcoat with red pigment applied to the mould. This was followed by two layers of matting.

Fibreglass casting from mould

The first fibreglass heart shell removed from the mould. It popped out very easily because the mould release was applied correctly this time.

The shell of fibreglass was very flexible and had to have bracing fitted inside to make it rigid. This was done by hot glueing pieces of cotton rope on the inside and applying fibreglass matting over the top. The front shell also had a steel framework fitted so it could be attached to the wing mechanism.

Internal bracing of heart shell

The internal bracing in the front heart shell showing the cotton rope before being fibreglassed.

Completed 3D heart

Heart shells join line covered with cloth tape and polished

Casting with Urethane Foam

Detail of a completed Ninja Snail

Detail of a completed Ninja Snail

This picture shows one of the completed Ninja Snail props made for The 52 Storey Tree House stage show. Twelve snails on a wooden tray were required for the show.

Because twelve were required their overall weight was of prime consideration. The construction technique chosen involved making a hero snail sculpture and then making a fibreglass mould. The mould was then used to cast the required snails in expandable urethane foam. The urethane foam had the advantage of a quick turnaround between castings plus being very light.

Small snail statue used as a base for sculpture

Small snail statue used as a base for sculpture

New plasticine head sculpted onto ceramic snail shell

New plasticine head sculpted onto ceramic snail shell

A small ceramic garden snail sculpture was found that had the correct sized shell. A new head was sculpted using plasticene over the existing snail head.

Fibreglass mould half

First half of fibreglass mould completed

Completed fibreglass mould halves

Completed fibreglass mould halves of the Ninja Snail

After carefully covering the snail with wax and building a flange along the centre line the first half of the fibreglass mould was made. A couple of coats of gelcoat was applied first followed by several layers of fibreglass matting. After the first half was finished the plasticene flange was removed and the other half of the snail cleaned and waxed. The second half of the mould was made in the same way as the first.

After letting cure for a day the fibreglass mould halves were removed from the snail sculpture. This step is usually glossed over in descriptions of mould making when, in reality, it can be the most difficult aspect of the whole process. It is very easy to damage the mould if it gets stuck in unexpected undercuts etc. Once released and cleaned up the mould is ready to prepare for casting.

Two mould halves bolted together

Two mould halves bolted together in timber support frame

Mould clamped and ready for urethane foam pouring

Mould clamped and ready for urethane foam pouring

The mould is first waxed and bolted together. A wooden frame is built around the mould so that it can stand flat on the bench. This makes it easy to pour in the urethane foam. A flat cover is made to clamp over the top of the mould after the foam is poured in. A few small holes are drilled in the cover to relieve the pressure buildup of the expanding foam.

It is a good idea to clamp the mould halves together as well to prevent them distorting outwards under the pressure of the expanding foam.

Mould cap clamped on after foam pour

Mould cap clamped on after foam pour

Expanding foam seeping out

Expanding foam seeping out of relief holes in mould

Urethane foam comes in a Part A and Part B which is mixed together by weight. You can also add a tint to change the colour od the foam. I chose a green base since the final colour was going to be green. Some experimentation is needed to work out the volume of mixed foam required that will expand to fill the mould (with some to spare). Once this is determined the two parts are poured into a container and thoroughly mixed with an electric drill attachment for a minute. It is then quickly poured into the mould and the top cover clamped in position. Within minutes the foam will expand filling the mould and releasing the excess out the vent holes in the cover as shown.

Casting removed from mould

Casting removed from mould before cleaning

Trimmed ninja snails

All the cast Ninja snails trimmed and ready for painting

After about an hour the clamps can be removed and, if mould release has been correctly applied, the casting should pop out from the mould. Again, this is sometimes not as easy to do as is often portrayed in “how to” videos. You will get quicker as you learn the dynamic of the materials. It is doing this part of the process that highlights how strongly you made the flanges of the mould. It often requires quite a bit of force to pop the mould halves from the casting and the mould can be damaged if it is not strong enough.

Foam inevitably seeps between the mould halves but this is easily trimmed off. The final step is painting the snails and air brushing on highlights. Small plastic eyes from Spotlight are glued in position under the ribbon masks. The ribbons themselves are folded in half and glued with some florist wire which allows them to be shaped as required.

LoL Cosplay – Janna

Janna's staff

Janna's Staff

We have recently completed a League of Legends Janna’s staff cosplay prop to be used at the upcoming PAX convention being held in Melbourne in July 2013. Hopefully we can bring you some photos of the convention. Janna’s staff is made from fibreglass and has a detachable pole to make transport easier. A detailed view of both sides of the staff is shown below.

There are those sorcerers who give themselves over to the primal powers of nature, forgoing the learned practice of magic. Such a sorceress is Janna, who first learned magic as an orphan growing up amidst the chaos that is the city-state of Zaun. Janna eked out what living she could on the streets. Life was tough and dangerous for the beautiful young girl, and she survived by her wits, and by stealing when wits weren’t enough. The rampant magic that characterised Zaun was the first and most alluring tool which Janna realised could both protect and elevate her. Janna discovered that she had an affinity for a particular type of magic – the elemental magic of air. She mastered her studies of air magic in a matter of months, almost as if she was born of it. Janna went from a street vagrant to an avatar of the air virtually overnight, stunning and surpassing those who taught her. Such a rapid ascension also changed her physical appearance, giving her an otherworldly look.

Detail of Janna staff

Seeking to right the injustice in the world (particularly the insanity that had become the city of Zaun), Janna has brought her talents to the League. She is a voice for the regulation of magical experimentation and a supporter of the development of techmaturgy, making her an indirect ally of the city-state of Piltover and the amazing techmaturgical minds that live there. Janna is also a new favorite of the League’s many fans. She is often the center of attention at functions, fan appreciation days, and other celebratory events. There is something untouchable about Janna, however, and her affections can change as quickly as the wind.

Janna - The Storm's Fury

Janna - The Storm's Fury


Do not be captivated by Janna’s beauty. Like the wind, she is one gust away from terrible destruction.

League of Legends cosplay characters at PAX Melbourne 2013

League of Legends cosplay characters at PAX Melbourne 2013

Giant Coffee Beans

Coffee beans Print logo

Print logo

Just completed making two giant one metre long coffee beans joined together in the shape of a heart. It was made for a local production company whose client, Nestle, wanted the large coffee beans sculpture to promote their Greenblend coffee product in shopping centres.

Coffee beans heart

The reference for the coffee beans was the print logo shown top right. The coffee beans sculpture was first carved in polystyrene from which a latex mould was made. The sections for the two beans were first cast in fibreglass from the latex mould. The fibreglass sections were then joined together in the shape of a heart and attached to a plinth by an internal steel sleeve. Construction in fibreglass was chosen because it would stand up much better to being transported from place to place and also the bumps and knocks to which it would be subjected.

More details of the construction can be found on this link.

Giant coffee bean sculpture

Completed giant coffee bean sculpture

Large Mould For Cactus

The technique for making a large mould has already been described in the post on making large moulds. A variation on this technique involves the addition of a sculpted polystyrene section to make the armature for the large mould. The object that was made using this technique was a large cactus.

Additional steps for the large mould

Again the basic technique is a plaster and vermiculite mix over a hessian covered timber armature. The only extra steps to make the large mould for the cactus involves using polystyrene to sculpt a part of the cactus armature that would be too difficult to make using templates. In this case the rounded top of the cactus was sculpted in polystyrene.

Step 1

Making a timber armature

Making the timber armature

Instead of using ply template ribs to define the shape we use thin strips of 4mm plywood. These are stapled between the top and bottom cross section shapes.

You could add additional cross sections if needed but this shape is simple and only needs a top and bottom.

The rounded top of the cactus was a little difficult to make in wood so it was roughly shaped from polystyrene. This was also covered in a vermiculite mix after being glued to the top of the base section after the main sculpting was finished.

Step 2

Covering with hessian and plaster

Covering with hessian and plaster

After the timber frame has been completed it is covered with a tight fitting layer of hessian. Next a thick layer of plaster is applied to the hessian. After this sets it makes a solid base onto which the sculpting mix can be applied.

It is a good idea to do as much rough shaping as you can when applying the plaster base coat at this stage. This will minimise the amount of sculpting mix that will need to be applied afterwards and also reduce the amount of sculpting work that will need to be done later.

Make sure you have thought through the logistics of how you will handle the armature as it will now start getting quite heavy.

Step 3

Sculpting the detail

Sculpting the detail

After the base section has been covered with a thick layer of vermiculite and plaster the finer sculpting can start. You can start before the mix has dried because it is a little easier to work. When all the detail has been sculpted the whole thing is given a light sanding.

Trace out the shape of the top and cut a block of polystyrene about 25mm smaller all around. This is roughly carved to the approximate shape which will then be fitted to the top of the timber frame.

Step 4

Finished composite shape

Finished composite shape

After the base section has been finished the polystyrene block that has been prepared is glued to the top of the base.

A layer of vermiculite and plaster is applied over the polystyrene and shaped to blend in with the bottom section.

The whole thing can be given a light sanding with fine sandpaper and put aside for several days so the plaster can thoroughly dry out.

Once it is totally dry the surface can be sealed with shellac in preparation for fibreglassing.

Step 5

Making the large mould

Making a fibreglass mould

When totally dry the armature is sealed with several coats of shellac. A wax mould release is now applied and polished to get a smooth surface on the large mould.

Since the cactus has undercut issues with the curved rib shapes in its surface a two part fibreglass mould cannot be used. To solve this problem a three part mould is used which will allow the mould sections to be removed easily from the armature.

The picture shows the completed fibreglassing of the first section of the large mould.

Step 6

Completed fibreglass mould

Completed fibreglass mould

The other two sections of the large mould are fibreglassed and, after bolt holes are drilled in the flanges so that it can be reassembled accurately, are removed from the armature.

The completed mould sections are given a sanding to remove any fibreglass splinters from the outside surface. This makes handling the large mould sections much easier and safer. This is an important step because, while not life threatening, fibreglass needles in the hands are very painful and you will be itching for days until they are out of your body.

Next the three large mould sections are bolted together ready for casting. Below is a completed cast of the cactus. The little horns were added after the main body was cast. Because the cactus was going to have lights inside clear surfboard resin was used so the fibreglass would be translucent.

Completed fibreglass cactus casting

Completed fibreglass casting

Making Large Mould Armatures

When big props or scenic elements are required for a stage show or special event a large mould generally needs to be made. Sometimes the mould can be made in-situ from real world objects such as tree trunks, a rock face or architectural elements rather than having the required object sculpted. This can save an enormous amount of time and money.

For smaller moulds it’s common for the armatures to be sculpted in polystyrene, plaster or clay. Polystyrene is the easiest to use but as the size of armatures increase so does the volume of foam required to make them. With plaster and clay it is the weight factor that becomes the big issue as armatures get larger. In most cases the major cost in making several big props or scenic elements is the cost of making the large mould armatures.

Considerations for large mould armatures

Usually a balance is struck when making large mould armatures between a cheap internal support structure and a thinner outer skin of foam, plaster or clay which is then sculpted to the desired shape. The method described below is a “Template” method for making armatures for large moulds. It involves connecting templates of different cross sections of the object together to make the initial armature base.This minimises the quantity of sculpting material required to make armatures for a large mould.

Step 1

Large mould timber frame

Making the timber frame

A rough shape is first constructed using ply templates to define the required shape. CAD greatly simplifies this task by providing accurate template drawings for marking out the individual section shapes. Use a solid base to build the framework as it will become quite heavy as more material is added. It is not a bad idea at this stage to attach four 100mm swivel castors to the base to make moving the armature around easier.

Always consider the logistics of moving any large object around before you start building. A little planning in the early stages can avoid all sorts of grief later in the process.

Step 2

Covering large object frame with hessian

Covering frame with hessian

Once the armature framework is built cover it with a layer of hessian. This can be simply stapled onto the ribs and battons of the framework.

We now have the basic armature over which we apply the sculpting medium. Hessian is the better base for plaster. If we were using clay, chicken wire would be the better choice because the clay can ooze through the mesh which holds it in position. Polystyrene, on the other hand, needs smooth flat ply facets so it can be glued in position. That can get a little complicated with large objects.

Step 3

Applying plaster for sculpting large shape

Covering with plaster

The hessian is now covered with several layers of plaster. It will need to be a thick consistency so it won’t run off the hessian. Make sure it bonds well with the hessian.

This forms the base layer of the armature and will need to be about 30-40mm thick. The basic shape of the armature can be roughly outlined at this stage.

Step 4

Sculpting large object in plaster

Shaping the plaster

Next make up a mixture of plaster and vermiculite. A 50:50 mix is a good starting point. The vermiculite makes the plaster easier to carve once it has set. Straight plaster is like carving stone. The mixture is applied and shaped as required and sanded smooth once it has dried out a little.

It should now be left a couple of days to dry out completely before the next step of making the large mould.

Step 5

Form ready for fibreglassing

Form ready for fibreglassing

After the plaster has thoroughly dried you can give it a very light sanding with fine sandpaper to get a nice smooth finish. Fill any small holes you find. The plaster is now sealed with shellac and several layers of wax is applied to act as a release agent.

Be fastidious when applying the wax release agent. By building up a smooth glazed wax surface now it will save a huge amount of unnecessary sanding work later if you happen to miss a section.

Step 6

Large mould fibreglassed section

Fibreglassed section

Because there were curved surface features on the object to be moulded it was necessary to make a two part mould. This ensures that the fibreglass shell can be easily removed from the armature. Any subsequent castings made from the large mould will be easy to remove as well.

The photo shows the finished fibreglass shell of the first half of the large mould.

Step 7

Completed large mould

Completed mould

Here is the finished two part mould of the large object. Since it is a symmetrical object we only need a mould for one half.

After casting two complete sections the two halves are fibreglassed together to make the finished object.

The making of large objects involves a huge amount of work. The making of the mould is the major expense incurred. If short cuts are taken with the mould it can lead to very expensive mistakes when the time comes for casting.