This is a simple modern towl wall hanger. It can be glued to the wall preferable with Nano Tape which leaves no residue when you remove it. And it glues extremely well.

I printed it with Overture Matte PLA on my Bambu Lab P1S with 0.16 High Quality and I increased the infill to around 30% and infill pattern Gyroid for more strength.

The little nubble can be put into the hole afterwards. It stays in very well without glue, but can be glued as well. This way you don't need any supports.