How small do you want them? A bunch of carnivores get kinda big and don't fit very well into a terrarium. Is there any particular reason you want a terrarium? Looks, super low humidity (ie 20-0%), nowhere else where they can get enough light?

pretty big because i have a sarrcenia Purple and a nepenthes ventricosa.

Neither belong in a terrarium. Especially the Sarr. The Nep will do fine treated like a houseplant.

CPs do not belong in terrariums.

Yeah, terrariums complicate things. Where do you live? Is the outside enviroment completely inhospitable to plant life?

live in NY

I do too. The weather is fine for the purpurea outside for most of the year. I grow my neps, or tropical pitcher plants under lights. You could call it a terrarium except it does not raise humidity, only light levels. The humidity is fine in NY for most plants.