The Lego Ferrari F40 project went further and better than I had imagined it could. The model looks fantastic, and my Lego skills much improved, but what it needed to be complete was a proper wheelset to match the early-mid-1990's racecar spec.
First explorations of the insert idea used simple paper discs to work out possible mounting methods as well scaling the detailed design to fit with the Lego rims and tires
Various tests with 0.10" styrene sheet proved the Cricut could handle the intricate spoke mesh design. Thickness for the spoke face, hub bolt, and mounting core was produced by stacking up individual layers of cut sheet. These stacks were placed into the Lego wheel parts to get a sense for the right scale and different depths of front and rear offsets.
Design refinements and dimensions were sorted and a large Cricut job fired off. Building the inserts from large stacks of individual part layers took quite a bit of effort. I'm not a proficient painter so getting a nice finish was probably the most challenging aspect of this project.
This test set of hand-assembled and painted inserts fit perfectly and look proper.
To make reproductions available to other builders, I worked the design's exact specs up in CAD (while learning Cinema4D) to send to Shapeways for 3D prints.