1 inch display post base

My kid is REALLY into tornado sirens. I'm modelling different types of them with simplified geometry for kids. They're designed to fit snugly onto this post, but this post could also be used for anything you wanted to display that has hole to accept a 1 inch (approx 27mm opening) diameter hole.

I suppose it could also serve as a pretty useful stand for other objects, like busts, helmet reproductions, etc.