Terrarium(s) - small or medium?

I'm suddenly obsessed with building a jam jar terrarium. I spotted one in The Simple Things magazine. I have several jam jars in my recycling bin at the moment. I'm going to pull them out, soak off the labels, and run them through the dishwasher. I'm not going to make several at once; but if I like the process and experience, I'd like to keep some jars on hand for more.

Anyone have experience with terrariums?

Limited experience, primarily with terrariums (terraria?) assembled by others, using inert materials and air plants. Mostly I've not found the knack of getting them to thrive, but the few that seem to do well are in medium or small glass containers. The air plants seem to do better when contained, but the container having an opening. Earlier I was trying to set the air plants out in the open air.

So, limited, but I love how they look when they flourish.