ELFA-Compatible Hook Profile

This is the basic profile of an ELFA shelf hook, for building your own designs on top of. It prints fine "lying on its back" without supports, assuming your printer does OK with overhang, or "on its side" with supports.

For an example, see my [ELFA Cable Management Hook](https://www.thingiverse.com/thing:3481102).

Should be compatible with all other two-slot vertical standards (Rubbermaid, Closetmaid, etc).