Step 1: Get Some DICE
then buy some valve covers or use the ones that you already have on your bike or car.
Step 2: Clamping..
get your drill ready- if you have a drill press this will be easier..
I used a 3/8 inch bit to drill it. try test drilling into a piece of wood, then try the cap into it..
once you are satisfied with the size, drill into your dice. you are going to have to drill as far as you can without going through. drill small amounts at a time and test fit, or use the depth indicator on your drill press.
Step 3: Tight Fit?
Step 4: Glue
put a small mount of glue around the bottom of the cap, so when you push it in, the glue gets scraped upwards, over the rest of the cap.
Step 5: Let It Dry
make some more for your other wheels.