While ago, i built a sheet metal brake from scrap. The design is simple and effective.
To build it you only need:
- Three pieces of L profiles, equally cutted (In my bender 3x1 meter long or 40 inches);
- One robust weld-on hinge (splitted in half use a piece for the left side, and a piece for the right side);
- Two pieces of threaded rod (25cm or 10inches);
- Minor profiles for the supporting stand and for the lever;
I've only used an angle grinder to cut the pieces and a MIG welder to compose the sheet metal bender. This tiny sheet metal brake can easily bend a large sheet metal of 1.5mm (3/64") or a narrow (5cm or 2") but thick bar (5mm or 6/32").
I'll improve it soldering on the back side two removable and adjustable stop bar to hold the upper L profile in place: while bending also an horizontal force is applied and sometimes the friction force applied vertically by the threaded rod is not sufficient.
The only drawback with this kind of sheet metal bender is that you cannot bend on four side, only on opposite sides. If you need to build a box you have to assembly it in two pieces, like the model in the photo:
The bending lever arm is 60 cm or 23 inches, and is sufficient to apply the right force to bend the metal.