Lower the ceiling. If there is a 3-block gap, players can often jump and glitch through the piston arm.
Tip: You can use Redstone Repeaters if you want a slight delay, but for a "Lovely Craft" style achievement, instant activation is usually better. lovely craft piston trap achievement guide full
The goal is to create a 2x2 square. When a target steps into the center, they trigger pressure plates that power pistons. These pistons push blocks inward, pinning the target in place so they can’t jump or move out. Step 1: The Layout Lower the ceiling
Place one on each of the four sides of your 2x2 square. lovely craft piston trap achievement guide full