A tool made in 15 minutes that will help you cut perfect V-Groove in polystyrene foam. The groove will help bend the foam.
It took less than one hour from the idea to the second build I made (I made a second build so I can take pictures to document it). Nothing to blog, but the result is exactly what I wanted: cheap, made with thing I hade available here, it solves the problem with a perfect result.
Cut the first piece of wood
Cut a 60 to 80mm long piece of the first bar of wood (the 35x50mm one), the cut it at 45° across the middle of the 35x60mm side
Flip one of the pieces
Your cut is probably not perfectly perpendicular to the side of the bar (remember: this a quick and dirty build), and then the edges are far from being parallel when you align the pieces:
But remember, this is also a perfect build. So flip one of the pieces to correct the problem:
(Thank you God Of Geometry)
The space between two pieces of wood must be equal to the width of the groove, that is twice the depth of the groove for a 45° cut. (I want to make a V Groove in 6mm foam, so the groove will be 4mm depth and 8mm wide).