This thing was made with Tinkercad. Edit it online https://tinkercad.com/things/h31fj3GpuZPThe hexagonal area at the top is where the brush goes, bristle up. The hole in the top that leads to the inside, which is hollow, is where either the cartridge, single edge, double edge, or straight razor goes. It's even big enough for big handles like the Merkur Futur. And now it's easier to print than ever before. I removed the tinkercad logo from the bottom and split it into two pieces that are better for printing without support.