I was worried about not getting air movement to the orchids, so I looked around and found another tiny terrarium. This one has little hinges like you see on the back of photo frames that hold the glass in. I removed the top two triangles so lots of air can get in there.
The main reason I need glass for the minis is because I have two very large, fat cats who love to eat things. I must keep them away from my babies.
I left the other two in the other terrarium, and they are doing just fine. In fact, if you look closely, you can see the little wee spike coming out of the Oncidium pusillum (whispers silent prayer that it will survive).