You will design a 3D CAD model and mill it on the 4 axis CNC.
Export you model as an .stl or .igs file. An ideal form would be a double-sided part or a longer/round-ish shape.
The project can be one or multiple parts. Take into consideration tabs, how to remove them afterwards or live with them. The stock material can be flat or round.
The part(s) can be cut from any of the Roland approved list:
Chemical Wood (Soft)
Chemical Wood (Hard)
ABS (these settings work great for Delrin)
Document and blog the original stock material, CAD screen shots, in-process milling images, and final part shots.