Once built, wait for a mob to approach. A wandering zombie, skeleton, or pig will walk onto the pressure plates to reach the bait.
Before entering the achievement zone, ensure you have the following baseline items in your hotbar: lovely craft piston trap achievement guide verified
This is a simple final step once you've unlocked the Rocket and Beads. Simply drag either item over a character in the game world and release to "hit" them. This is a straightforward way to clean up the last achievement. Once built, wait for a mob to approach
Allow a hostile mob to chase you into the corridor. lovely craft piston trap achievement guide verified
Ensure your world has Cheats Off and is not in Creative Mode. Achievements are disabled the moment a world is set to Creative.