Spent a few hours adding a base and sides to them, for storing the cupboards full of tools I have acquired over the years..
Base for the Ply shelf by brf, on Flickr
9mm Ply base by brf, on Flickr
Bench #1 with base, sides and back by brf, on Flickr
Then did the same to the second one:
Adding a base to Bench #2 by brf, on Flickr
My re-cycled fence posts are pretty warped:
Warped fence posts by brf, on Flickr
Fairly slap-dash, but good enough to stop stuff falling out the back etc:
Bench #2 by brf, on Flickr
Next step is a shelve above one bench about 18″ up and half depth for storing things like battery chargers etc.