Mandalorian TBS Spear Ring

The Black Series 6" Mandalorian figure is fantastic. I recently started making a spear for the figure using a kebab stick.

I decided to design and print a ring to fit on Mando's back to hold to spear in place. The peg fits into the rectangular hole on the figure's back.

The inner hole is designed to fit a 3mm kebab stick. I couldn't, however, find a way to keep the stick from going all the way down.