I made these two mounts, works for 1080p and 720p models.
It bends a bit due weight, but not so bad imo.
I have one hole drilled to concrete wall, screw there and some double sided tape.
Screw holes are ~3.5mm.
Smallest one has ~5mm hole for screw, for camera ~3.5mm hole.
I used 4 perimeters, 4/4 layers, 20% infill, pla.
You may play with settings.