Sorry to tell you but cacti & succulents would do horribly in a Terrarium. Two fold reason, they absolutely need drainage & air circulation neither of which are available for the plants in terrariums.

Yes, C&S in Terrariums are trending now, but doomed to fail & thanks to all these sites showing them like Pintrest, folks will buy these & have them die quickly or make them themselves as you seem to wish to do, only to have them die in sort order.

For further confirmation of this, pls. read Cactus & Succulent Forum, search there for Terrariums & read.

Lena