This is a lovely winged uke hanger for your wall. The holes are roughly the size of a standard drywall screw and that's what I used to mount it. I think ukes are light enough not to bother with anything more substantial, but it's your call.
There are two versions. One has buttresses behind the horns to support printing without added supports. I've printed both with & without supports and they both are functional. The buttresses seem to keep the back of the horns clean. I painted them with acetone to bond the layers and dress it up a bit.
My printer settings for this were:
0.3mm layer height
Hung with drywall screws but you could use other anchors depending on your wall and confidence.