Nice and simple hexagonal rims / sleeves / protectors / covers to put on round dumbbell weights (adjustable dumbbells). Stops from rolling around and looks nice.

I haven't seen adjustable weights in hexagonal shapes, and would not care much for non-adjustable weights.

There are 3 variants, flat, rounded which are recommended and "circular" as an experiment. Rounded and circular are for the round-sided weights. And flat is for, well, flat weights.

Biggest one uses about 50g of filament. Technically one for each dumbbell would be enough but that would look weird. 

For best results use the cadquery python file provided and edit the numbers but you can also just scale the step files. Fit should be tight enough to not rotate and the round ones snap in place (with force).
The thinnest part of side walls are 2 mm so there's room to scale as needed.

Test before printing many and watch your fingers when assembling.

Pairs nicely with the Dumbbell nut I made.