Fill your glass with a layer of rocks to create the base of your terrarium. This will allow for drainage of water and ensure that your succulents stay nice and dry after each watering. Gently arrange the rocks in the bottom of the terrarium as to not break the glass. Pull the succulents from their containers and loosen up the dirt and roots. Arrange the plants in your terrarium and use the leftover soil from the planters to fill in the gaps in the soil. Try to keep the soil off the succulents as much as you can.