Not much to them, good water pump, mini sprinkler heads and water proof box with spots for the clones, for $60 its worth not having to make your own and if it does have a prob cheap enough to replace the pump that breaks..
I've done thousands of clones and just as easy to use r/w cubes or root riot plugs in tray with dome (if you need the humidity at begining), you also lose fewer due to the various probs with clone machines, like power outages, water ph flux, clogged lines/heads, ect. When there is no probs, machines are cool and work good and if your new to clones they can be helpful but the old method is pretty reliable, easy too.