I designed a really simple, easy to print rotary tool lathe "bit" you can use to shape soft materials like foam for model making. It helps me create symmetrical prototypes super fast!
Here's a video of it's prototype version in action
All you need is a larger rotary tool adapter, which is basically a large, heavy duty version of the common cutoff wheel bit.
This is the exact one I used below:
Gyros 80-18105 Mandrel, 1/8" Shank - Stainless Steel, Fits 1/4" Arbor Holes. For Dremel Type Tools
Next you can print out or make a clamp to clamp the tool to the desk. Then just hot glue your object to the printed part and you're all set! Make sure to wear protective safety equipment to protect your eyes, lungs, and face. Be safe and enjoy!
0.2mm to 0.3mm reccomended
STL File is designed in mm