This adapter is sized for my particular Miter Saw (a Kobalt from 2015-ish) to the hose on my Shop Vac (a Ridgid hose from this kit).

The outer diameter of the Miter Saw end is 55.5mm; the outer diameter of the Dust Hose end is 53.5mm. Both taper somewhat towards each other to help them fit snugly into their respective parts. The OnShape file is here, in case you'd like to tweak it to your particular tools.

The dust bag that comes with the saw still fits the adapter (though a little higher up than the dust hose), so you shouldn't need to take this off once it's on.

I printed this in PLA, and have had no trouble with it being strong enough so far.