Those benders do work but you can only do straight bends or "folds" a bit like a "Press brake" will do when working with metal.. but this you can do by clamping your plastic between 2 bits of wood with clamps and heating (not to high) in an ovan. i used that way forming the roof and sides of some coaches i made for my HST 125.. i used a sheet clamped between flat board and a wooden broom handle heated in a closed oven for 10mins at 140 then pulled the sides around the broom handle to get the curve between the sides and roof