I have completed the "manufacture" of the central, removeable, septum. The making of the two struts was comparitively easy. Instead of planing down two pieces of mahogany to fit, I used a few few scrap pieces of walnut which is just as strong and workable. The bellows section is made using standard cut widths of plastic reinforced card with thin, slightly elastic, cloth on both sides. The two holes (3mm) were drilled through the whole assembly when glued to the two mounting struts. Attempts with commercial (dress shop accessories - knickers elastic?) elastic were not succesful as the diameter of the elastic prevented even expansion and compression of the bellows folds. I removed the outer material cover and found 10 1cmx1cm core rubber strands, which, grouped into 2 x5 rubber strands (glued at both ends) worked perfectly. The expansion is more than 3 times the length, whilst the "knickers" elastic could only manage around 2 times. This rubber will not last for ever - but is quite easy to renew at some stage. The range of dimensions I have now (lens board to GG) is 7.5 cm to 28cm - actually the full range of the camera without using the base extension camera. I enclose some photos. I have not trimmed the loose ends of the rubbers or of the outer edges of the bellows, so the construction is a little more understandable.