Cactus Terrarium Tutorial

If you remember before Christmas, I had mentioned I was going to make the girls fairy house terrariums from Santa. Well, I did do that, albeit at about 1am on Christmas Eve... uhhh, such a procrastinator. But they came out great:
And, now I am an expert on terrariums, so your tutorial begins here. These are your supplies: You need gravel or rocks(I bought mine at a craft store for $3), sheet moss (also from the craft store for $2-$3), activated charcoal (purchased in the pet store aquarium aisle for $6), soil and sand (I had this on hand), an open, wide mouthed glass container (Goodwill $1), and I had to use some cute figurines for mine which I got for a steal from a great website called Miniature Gardens. Of course my girls love fairies so I got some of those, a gnome for Ariana, some great doors, tiny lady bugs, frogs and butterflies. I could have gotten a ton of stuff from there, but I kept it to 3 terrariums.
Now, I am telling you how to make a cactus terrarium- there is a difference between these and a moss terrarium. With a moss terrarium, you can keep it moist and keep it covered. The cactus terrariums need to be kept fairly dry and do not need a lid. We clearly went with the cactus version since it is wayyy easier to maintain. Moving on...

Wash your container very well first. You then want to mix 2 parts dirt to one part sand (again, this is only for cacti, not regular house plants.)
From there you want to add 2 inches of rocks to the container.
Then add 1/4 inch of the charcoal, this will keep down odor and filter the water.
Now add 3 or 4 inches of your dirt/ sand mix.
Add your cacti in a pleasing visual arrangement.
Add your figurines and then voila:
You will notice that I did not use the sheet moss. The moss works well in a regular terrarium as the moisture will keep it green and fresh. In the cactus terrarium, it will brown and add more of a tumbleweed feel, which I did with the other 2 and it looks great. I just decided to try this one without. So, you can do it, right? Pretty easy... right, Nap Mom?