As 248F1 and RB5 builds are heading towards finish line I need to make new brake rotors, hats and calipers. F2007 and MP4/22 also need those. Started with rotors. I've been thinking about how to machine square venting holes using round milling bits. Came up with 2 halves design. Made quick 3D CAD model to check if design would work. I wrote g-code by hand to control my CNC. Having rotary table made it quite simple. Plan is to make metal masters and then cast number of resin copies for all mentioned kits.