This is a modified version of my old Reuleaux Triangle design. Instead of screws it uses snap fitting pieces to hold the 3 layers together. Therefore it is a completely lazzzorcut design :)
The "screwlessness" was inspired by the "Screwless Cube Gears" by emmett http://www.thingiverse.com/thing:10483
Cut the releaux_triangle_snap_export_final.dxf file. The other file also includes help lines which are handy to have if you want to change the design but you don't want them to get cut.
The design consists of 3 layers:
I used 2mm Delrin for the middle layer (the one with the Reuleaux triangle) because it feels nicer, but acrylic would probably work too except for the small snap fitting pieces which will probably break if you cut it from acrylic.
The top and the bottom layer are identical and I normaly cut it from 2mm transparent acrylic.
Snap fit together like shown in the picture and have fun while rotating it in the square :)