Kendamas are a popular Japanese cup and ball game. When I first started at the IRL, I bought a ball and combined it with the physical grip of a 3D printed kendama that my coworker Jake created for me on Fusion 360 .
** There are fully modeled free files on Thingiverse now from other creators now like: https://www.thingiverse.com/search?q=kendama&type=things&sort=relevant
I recently cracked my print when I was practicing. This is the process of how I fixed and upgraded my Kendama.
Step 1. To fortify the grip I filled the holes up to the top with toothpicks and super glued the top of the 3d print back in place
Step 2. I wrapped the Sarado (cups part of the Kendama) with electrical tape, being careful to avoid the hole where the string comes out.
Step 3. I wrapped the tape in purple string for visual reasons and super glued the ends to down to the print.
Step 4. There were uneven surfaces on the plastic body from the brush-on-finishing getting hit by the ball so often.
To cover these dips I sealed the handle with a similarly colored nail polish.
Just like that, good as new!! (And shiny!)