A small brake, 2 7/8" capacity (why in the world didn't I make it 3"?) It's useful for bending and creasing cardboard,plastic and thin metals.

I made this brake to bend up aluminum for a miniature dumpster. I printed mine at 50% infill to be strong enough for the stresses, so I don't know how it will hold up with less. Use a small rubber band and a toothpick to attach the handle to the nib as in the photos. There is slop in the connection from the nib to the die to make sure the right pieces are doing the work.
For thicker or tougher materials, I had to give a little help to the piece by pulling up on the edges while bending to get a tight crease and sometimes I bounced the pressure on the handle a little to coax the bend. The tool may benefit from a steeper angle on the knife edge and mating female die to over bend the angle so the material springs back to the desired finished angle. You will have to model this yourself. One way around this is after your piece is bent, take it out of the brake and put it on its side on a flat surface and apply pressure to bend to your desired angle by hand. Since the piece is already creased, it works pretty well to change the angle this way.

Die.stl is for making a rib in your piece. I don't think many will find this useful, but I wanted to illustrate you can make custom dies for custom forms. A useful die to make would be one to make miniature corrugated sheeting by creating a wave form. 90die.stl will bend your piece mostly at a right angle and is probably the most useful to most people.

After printing either of the dies, I trimmed the edges with a knife because they bound a little in the body without it. Only trim the ones that touch the body, not the edge that does the bending.

I printed my handle with the peak down and the sphere cutout up. I rotated it for the upload because the peak pulled away from the build platform during printing. If you choose to rotate the piece to print, I'd suggest printing the handle with a brim to keep everything glued flat until it gets some buildup.
Enjoy:)