Here is the basic set up for a scorpion, however, my terrarium is large compared to most housing a single invertebrate.
Due to the varying species of scorpions, it is best for you to research the long-term care of your specific species. If you own Australian species of scorpion, I'd advise you to look at "http://www.thegreenscorpion.com.au/showconcats.toy?cnid=44056" with regards to long-term care. Hwever, no matter the species, the caresheets on the website will provide useful information.
Step 1: Buy the Stuff
The things you need are:
1) A tank (terrarium or fish tank with a sealable lid with vents)
2) Sand or other substrate such as Coco-Peat (must be clean, try your local pet shop or online)
3) Leaves, bark, small sticks, rocks (anything a scorpion can hide under or climb on but ensure they are clean)
4) A very small dish
5) Cotton wool
6) Crickets or cockroaches (food)
7) Your scorpion(s)
You will also need a terrarium heater light to heat the tank and provide UV light to the scorion.
P.S Small scorpions can climb on glass, so if you get small scorpions make sure you get a tararium that is "escape" proof
Step 2: Putting It Together
Start with your tank, put about 2-3 inches of sand (or other suitable substrate depending on species and origin of the scorpion) in it and place your bark, rocks and branches/sticks in the tank (make sure you leave plenty of space for the scorpion to walk around, but you can put as many leaves in as you want)
Next, Place the dish in the corner of the tank and wet the cotton wool (make sure it is VERY wet) and put it on the dish. This is the easiest way to ensure that your scorpion does not drown.
Step 3: Give Your Scorpion a Home
FACT: Scorpions will glow under a UV or "black" light.
Step 4: The Finished Product
You've finished your scorpion enclosure. You scorpion will be very happy.
Good Luck with your scorpion.
P.S. You can keep up to eight in a terrarium the size of the one I have. But you can keep 2-3 in a small sized tank. However, I would personally recommend that you only keep one scorpion per tank to avoid any conflict between tank-mates.
Step 5: WARNING!
Also, if you don't like arachnids, don't get a scorpion because they are arachnids, but remember, they are NOT spiders.
P.S. Some scorpions are very poisonous but be very care because even if they are not very poisonous, you COULD be allergic to their venom.
The scorpion used in this instructable is the Australian Flat Rock Scorpion (Yes, Australia does have scorpions) and it is not deadlybut the sting is very painful (Trust me, I know from experience).