Snap in hook for String shelves

This is a remix of the superb Snap in hook, made to fit *[String](https://stringfurniture.com/) shelving system*. I've made it slitghly thinner to better match the wires used by String, and also phased of the corners a bit so you don't scratch that expensive shelf.

The hook snaps in to place and fits both the standard and the smaller pocket versions.

I printed with rPLA from [Lostboyslab](https://www.lostboyslab.shop/) and 100% infill just to give it a little more strength.