Thought someone would have replied by now. Actually, I don't have a terrarium yet. I'm planning to start one this winter, though. In the interim I've been trying to read up. I'm not sure where you got your list, but it's different from what I've come across and read.

If you're planning on building a moss terrarium, you'll need the following:

moss

base layer of pebbles

filtration moss (basically dried sheet moss) - though my understanding is you can use charcoal instead

peat moss mixture (or potting soil)

spray bottle to mist the moss

glass container with a lid (really any jar with a lid, make sure it's shallow and wide versus deep)

If you want to check it out, there's a book called Tiny World Terrariums. The authors are the owners of a popular Brooklyn-based terrarium store. In the book, they list the items I wrote above. I just added the charcoal and potting soil as I've come across those two as alternate items.

According to Moss Acres: "Be sure to use a soil that drains well at the bottom (add sand and
gravel), but also make sure the clumps of moss are pressed
firmly into wet soil on top to make a good bond -
moss does not do well with air space between it and the soil."

Also, make sure that your moss terrarium gets enough light.

Again, I'm new to this myself, but this is what I've read. My plan is to build a small, rather basic terrarium using the materials I listed above. Hope what I wrote helps (and perhaps someone else will chime in with some advice).

Best of luck.

You do not need a terrarium to keep the Selaginella alive. Any glass jar with a lid will do. I like to burn a few dollars and get one of those glass jars for the kitchen, generally has a glass lid.

Initially I would just place the potted inside the jar if it will fit or depot and plug in the plant with

the soil into the jar. It needs distilled water, not tap water. Get a spray bottle and fill with distilled water and give it a good spraying after having put it inside the jar. put on the lid and

place in an east facing window where it will get some morning sunlight. Do not worry about

water condensing on the inside of the jar. What matters is if a white growth appears as that is a fungus. at such a time if it occurs open up remove what you can of it and leave the lid off over night. then cover in the morning. once you get the right amount of moisture in the jar it will only need a little water every now and then.