This just happened to be the right size for the hose on my Parkside stainless can vacuum and I've been looking for something to help cut down the amount of dust when drilling, this does the job nicely. It fits perfectly but I think I still need to smooth out the face that touches the wall as the hose is unusually heavy so it has fallen off a couple of times.
I use Makerbot Desktop with my CTC printer and initially it wanted to support the top of the 'donut' as well as the centre section but I thought that removing this support material would be messy and frustrating so changed the support angle to only support the centre section. There were a few tense moments as my machine isn't great at bridging (I still haven't fitted a filament cooling fan) but it bridged the gap successfully with only minor mess beneath.
89 degree support angle with Makerbot Desktop.