Simple tennis ball holder that holds 3 balls. It's strong, and has a fun design that allows it to still be strong through the power of hexagons. It also includes a cap that friction-fits on top for storage, or on the bottom if you have it open and want somewhere to put the top.

I printed mine in white marble PLA but ran out near the top so switched the last 15% or so to a red PLA and also printed the top in the same red PLA. In my tests PLA is fine for this application, sitting out on a sunny day it didn't wilt or anything.

For printing, I used 0.2mm layer height, and for strength I did 6 wall loops and 25% infill (in Bambu Studio this is the ‘strong’ preset). Print the tube standing up and the top with the wider side down onto the print bed.