An Airless ball without supports, which prints perfectly fine in PLA or TPU (recommended PLA Flex). If you want a harder but less flexible ball, I recommend using PETG or ABS, but if you want a flexible and shock-resistant ball, you should use TPU 85A or TPU 95A (TPU 90A may be too soft). Recommended to print in 50% silent mode, as printing with TPU could cause clogs and stringing (should turn off Z-hop when printing with TPU to avoid stringing)