It was a straight forward design made from 16mm square steel with the aluminium insect screen secured by a 13mm steel framework attached to the main frame using 5mm countersunk stainless steel screws.
As is usual with older homes the doorway was not square. It was tilted ~8mm from the vertical which, although it seems a tiny amount, becomes glaringly obvious when fitted with a rectangular frame that is square. Building a crooked frame to compensate for this requires a lot of patience and care. It can be quite stressful once a door is made and being installed wondering if it will fit as planned. It is a great feeling when everything is bolted in position and all the gaps on both sides are uniform.