The icosohedron (D20) was a challenge part I set my sights on when I started out with the PNC. The shape is complex enough to require a basic understanding of 3+2 movement and toolpaths, so I built up to this part with simpler programs. The final was cut with a .125" endmill with a long tool offset, and had to be run slowly to reduce chatter. This part was machined and parted off in one operation, using the shoulder of the tool to produce a smooth finish on the sides.