It works by preventing the snaps from being able to close. To install, tighten the bolt to pull the plug out of the way of the snaps, to lock, ‘loosen’ to push the plug up against the metal spring piece, locking the cap in place. I have tested on a Model Y Performance, the design likely needs to be modified for other models.

Printed with PLA on Bambu Labs X1C

Required:

• 4x M3x40 socket head cap screws (ideally stainless steel)
• 4x M3 heat set inserts + tool to install (soldering iron works great)
• 4x sets of printed parts
• 2.5mm Hex driver
• CA glue (ideally thin)

Assembly instructions:

1. Remove caps (if you are lucky enough to still have them)
2. Drill hole in cap using 2x printed parts as a guide. Space out the two parts in Z as much as possible to get a nice centered/straight hole. Can push the part out again from the front side with a bolt/drill bit/hex key.             
3. Heat set inserts into the plug, should be flush/just sub-flush with the surface.
4. With the countersunk side down, install the retainer piece + bolt. While this should be a friction fit, I used a few drops of thin CA glue around the edges to make sure it doesnt go anywhere. Be careful not to get any on the bolt itself.
5. Install plug + metal clip, to install on wheel, plug must be all the way down to allow the clips to move.                                                      
6. Install!