I decided to edit sphereinabox design to fit a bit better on a skateboard. Link to his original design: https://www.thingiverse.com/thing:151216
I then printed these in Nylon 910 Alloy by Taulman 3D and sent them Braille Skateboarding's way to test out. You may need to tweak the tolerances in the openSCAD file to work perfect on your skateboard and print best on your machine. I suggest printing one wheel in spare PLA filament to make sure it is to the dimensions you want before printing all 4 in a more expensive material.
If you want to enter to win, or see how they were made, watch this video: https://www.youtube.com/watch?v=f_3ayISNeiM