Love the water refill idea. Makes it easier to refill without having to disturb the colony.
Going forward, I would change one thing to make this design more efficient. Cut the tube so that it doesn't go beyond above the upper lip of the cover that way you could stack this if you make more.
you give me more ideas haha. a 1 inch tube to drop in food from above to a petri dish below perhaps?
Yeah, not a bad idea, gonna have to make this the top one though. LOL See, when I was doing the cuts, I accidentally made the whole in the lid a little too large, so there is a gap. The lid covers that up.
And for the food drop, do you mean, just something on the side to drop food in? Make it so I don't have to un-stack them.