Hi, this is a trap that is super funny to watch people get trapped in. It is also easy to build.
Step 1: Bottom of Trap
I made my trap7x7 with piston facing up all the way around except for the corners. Then redstone in the middle.
Step 2: Center of Trap
For the middle of the trap you lay a floor of any type of block. Then cover it with pressure plates.
Step 3: Top of Trap
For the top of the trap I used some fence posts and then some half slabs. HAVE FUN AND ENJOY!!!