This is a derivative of the kind of flexible hooks you may see in the organization section of a store. Modeled from scratch.
The "Egg" or main mounting body I'd recommend printing in PLA or ABS in 100% infill. and is easy enough with no supports needed.
The flex part on the other hand... Well that's tricky. You have two or three options:
Print the entire thing in one piece. I didn't test if this could be done with no supports. But when you use flex material like ninjaflex, it's pretty darn hard to remove. Had to toss it away. If you can howere, I'd recommend that (say if you printer can print separate support material, or you have a technique for flex stuff). Then adhere it to the slot on the egg, more on that later.
- Print the ones in parts, and stick them together. I'm not sure what works well for ninjaflex, but I heard, "not much", so used the same method I used for adhering it to the egg. More on that next. (Though, I'm sure something like Gorilla Glue may work well...).
So how did I adhere it all? I used a heat gun. I melted down the two parts of the flex hook part and stuck them together when they were nice and gooey looking. Then, to the egg I applied some crazy glue and I heated the flex material to gooey and stuck them together. Crazy glue may not have been needed, but still.
Of course the hook part was also printed with 100% infill and standard settings for ninjaflex.
The backing will still need adhesive to your wall.... so do that as you see fit. I bought a 20-pack of command adhesive strips for this and other store hooks.