I made these real quick for my own workshop. 
They are custom-made for my specific wrenches (the wera joker switch 6001) but should fit any other metric ring wrenches as well. 
Note that they are for 15deg angle.

I printed them upright (just how you would hang them) with supports just under the hooks. 
It is not needed to support the Hex heads, but you might get a cleaner result in the end.