I designed these feet so that they can use squash balls. Simply insert them into the original feet. Maybe it will work with the Ender 3 V3 Plus or K1/C. I haven't tested it and don't know if the same feet are "glued".
I printed it with Jayo PLA-HS Layer 0.20 / 50% filling (I want to try it with 10-15% and PETG) and supports on.
Squash ball: https://www.amazon.de/dp/B00QWUZJLC?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1&psc=1
The author marked this model as their own original creation.