On my shop vac, this attachment clip has been broken for a long time. Being an interesting shape, I decided to model it. The replacement fits very tightly on my vac, 

I printed this in PETG and 15% Infill, with the areas around the pins and the hooking part modified to 50% infill.

I also printed this laying on its back, so that the layer-lines would point in the direction of the force excerted. I would not do that again, the layer lines are way to visible. Better hide them on the inside.