Advice for making a little syngonium terrarium with this?

I have some small syngonium cuttings and wet sticks pretty much ready to be planted, and I’d like to put some in this terrarium. It’s not a fully enclosed terrarium, the front does not have a panel.

I’ve never made a terrarium before so any advice is appreciated.. like growing mediums to use and how to keep it humid and wet. I was thinking of at least putting leca at the bottom of whatever medium I use? I’ve never used leca before either but it seems like a good idea