I have just uploaded a second model which uses 1/2" (12.7mm) ball bearings instead of the 5/8" (15.875mm) ones if you prefer lighter weight or can't find the 5/8" ones.
It uses three 5/8" ball bearings as the weights, which is 15.875mm for everyone else in the world. These were originally superglued in, I left the ends open because I think it looks and feels better that way, but I redesigned it to be a little thicker and the balls now just snap in and hold just fine.
If you made one, post a photo! Thanks!
You may have issues with warping, if so just put a ~3mm brim around it and it should be fine. Printed in PLA at 200 degrees.
Rotate the model 90 degrees on the X axis to print flat, sorry about that.
You will need:
1 "Skate" 608 bearing
3 5/8" (15.875mm) Ball bearings (10 pack for like $4 on Amazon)
3 1/2" (12.7mm) Ball bearings
The skate bearing and ball bearings just press in, you may need to sand or file down the inside for the skate bearing to fit depending on your printer.