Seat frames/springs I do the most frame/spring jobs by myself. I bought some helpfull tools over the last years which make the job much easier. The only thig I dont do by myself is with the small coils with thin whire. Therefor I have a company I can order the common seatframes also with custom spezifications fitting on bodylenght and wheight.
Here are some tools I use.
Great osborne tool for vertical bending of ZigZag-Springs (need 2 of them):
for bending Springwire:
clamps for attaching wires or springs/making a bypass (there is a special pliers for it but you dont need it necessarily
There are also some other clamps but i dont know where you can get them. They are smaller and are fixing the springs at the metalband frame. But I only have my own stock on hand.