Epiphytes make for great terrarium plants since they mostly live on rain water and secure themselves to trees (hence, epiphyte). Some are parasitic and won't be such a good choice. For this Instructable, I'll be using a Ball Moss plant (Tillandsia recurvata) which is common through the Southern portion of the US. Ball moss is not a moss at all. It's an epiphytic air plant that secures itself to tree branches, lives largely off rain, and isn't parasitic although it might compete with its host for light. There are many epiphytic plants in the world. If you need some information or some sort of clue as to what to look for, call your local horticultural extension office and ask for some common plants that would work well in a terrarium. Do not harvest plants from parks or from other people's property without permission because it's illegal and not very nice.
Finding terrariums or making them is all about imagination and scanning through potential pieces. I spent 2 hours in IKEA scouting for possible terrarium ideas that weren't too expensive. There were some amazing pieces, but I decided against them for a cheap version.
This Instructable shows to make an inexpensive terrarium with found plants, and in doing so, I hope people can broaden their ideas about gardening, sourcing plants, and repurposing items. This terrarium is particularly good for beginners to gardening or building terrariums, but beyond that, it's pretty and easy and affordable.