I created this picture hanging wall hook to hang a digital clock I have. Every time I change the batteries, the nail gets pushed in to the wall and I spend a while trying to align the clock mounting hole right to the nail without it getting pushed in to the wall.
I printed this at 0.2mm, 20% infill. You could go 100% if you need more strength but it seems sturdy to me. I only made the single size but you can easily scale it up for larger nails.
At 0.2mm, 20% infill, this printed in 16 minutes for me.