When pouring epoxy on items where the epoxy will run off the edge, the item needs to be raised so the item does not bond to the back of the item. This is often called a bed of nails.

As an example, if you make a clock from old tree root slices. You would drive nails through a board to set the wood on, then you would pour epoxy over it until it completely coats it and the excess would drip off the edges on the board with nails.

This is a smaller version for doing jewelry or other small items. It has prongs sticking up and has a troth around the edge to catch run off.

Nothing special. But it's a good idea to coat with a mold release or spray wax before using so the dried epoxy can be removed.