Push fit onto dust port on a Makita 9924DB belt sander: slides on from the top. Designed for 35mm vacuum hose fitting, or a dust bag (held on with a hose clamp.
Vacuum port is offset to give plenty of hand clearance.
I printed with the rectangular face down on the print bed to avoid needing supports
I used 4x perimeter/walls so that the thin/med thickness walls printed solid