Make your own Captured Dementor

"Once they’re fully expanded, you’re ready to place your Dementor! Slide it carefully into the middle of the hydrobeads, being careful to have it centered and upright so you can see it well. (When I bought this, it was a keychain, but the keychain part easily popped out, so I removed it first thing when I opened the package.) Be thankful that you put the jar into a larger container, because those little suckers are slippery and bouncy and go all over the place! "