A simple snap-on shelf for Multiboard. It uses weight bearing snaps and features an angled lip around the edges for extra rigidity and to keep things from rolling off. 

The shelf surface is 130 x 95mm. It is not compatible with modular bin systems such as Gridfinity or Multigrid — it's just a plain old shelf.

I designed it to hold light objects, but have tested with a 500g battery and it holds up pretty well.