Customizable Calf Roller

I designed this based on personal experiences.
Personally, I am a runner, but every serious athlete has seen one of these before. After a workout or game, you roll these on sore muscles while applying pressure, and they help ease soreness.
At running events, everyone loses these, however. If you attempt to write your name on them with a sharpie, you end up with the sharpie on your sweaty legs. Since these devices all look the same, people regularly accidentally steal them.

To print this,