Today we cut the copper pipes (474mm long), 17 of them, along with 18little (24mm) pieces, each to connect the two right angle bends (36 of them!). The whole thing forming a ladder like structure. This structure will be placed in close contact with the copper sheet.
The pipes are now soldered together but when we tried to solder the pipes to the sheet, the sheet started warping up! We think this is caused by the heat expansion differential of a local spot against the rest of the colder sheet. Our thinking caps are on!