My main criteria is it has to be functional but it really depends what it will be used for, if you are just using it to pot up a few plants it doesn't have to be very big, a built in bin for potting medium would be useful, on one end a hole with a bin underneath to push prunings, old soil etc. through, a place to hang hand tools on the back wall or shelves to hold pots etc., maybe a peaked roof over it to keep the rain off if it's out in the open.

Mine is very simple, made up of half a sheet of 3/4" plywood hinged on posts in my lath house. When in use it hangs from chain on each end, when not in use I unclip the chains and it hangs down out of the way. When I start potting up 50 or more plants at a time I need space to work, nothing else matters.

You can get lots of ideas from the images below, hope this helps. Old barn boards, sounds lovely, a very worthwhile venture.

Annette

Here is a link that might be useful: Google Images

A sink of some sort, running water via a garden hose connection? Mine sits out in the elements against an old outhouse so not wanting to hang tools on it. If yours will be inside a garden shed, I'd add a tool rack, somewhere to put potting soil as mentioned above, shelves above and below. Drawers for pens/pencils, scrap paper or notebooks, balls of twine.

I always wonder how difficult it would be to keep the bench plus the garden shed floor clean when potting up plants with medium,etc.

Pinterest is THE place for ideas ! I want a roof over my potting bench -