The Short Story
After figuring out the bore and hub diameters, I printed hub centering rings for my car. They should be adequately durable if printed in ABS, ASA, or PETG with 100% infill.
I printed mine with Shaxon ABS at .28mm layer hight. Pumpkin orange. Because October.
Link to the parametric Thingiverse model I'm using: https://www.thingiverse.com/thing:40516
Link to the custom models I remixed from this: https://www.thingiverse.com/thing:4617312
NOTE: I've since ordered a set of injection molded ABS plastic centering rings.
The Long Story
Needing to keep the wheels concentric to the spindles, hub centering rings are a requirement and my kit didn't come with them. Some simple searches revealed the ring sizes I'd need aren't unobtainium but since the the car has two different center bores and hub diameters, one full set in each size are required if purchasing commercial sets.
Since I own a 3D printer I spent 5 minutes in Fusion360 modeling up two test rings to make sure I had my measurements correct before slapping down fat stacks of cash on commercial sets.