After messing about with slime blocks (I hadn't played Minecraft in almost two years until last week), I decided to build a trampoline. There are lots of great designs out there, but most of them aren't really made to fit into a world, or easily disguised as a building. I cobbled together a 3x3 trampoline with an on/off toggle on entry, as well as a glass door that closes when someone is inside the trampoline area. Let me know what you all think!