I needed an adapter for my 3M Xtract sander to hook it up to my 2.5" dust collection hose. This adapter is modeled to print without supports and fits the hose perfectly. It's a slightly snug fit, and the teeth grab well to keep it in place.

Don't want to worry with printing your own? Buy one already printed from my store: https://createdworkshop.com/products/copy-of-3m-xtract-sander-to-ridgid-2-5-shop-vac-adapter