Mad Max Style Post Apocalyptic Football Pads, dimensions: 99.11 x 66.71 x 61.91mm or 3.90 x 2.63 x 2.44in
This was designed to fit a 1/6th scale action figure. You will need to scale it up or down a little for a good fit. This was test printed for the figure, minor dimensional tweaks made to fit.
Printing this in resin with a flexible material would be ideal.
If you need my help to make fit what project you want to use it on let me know.