Purchase black ink from the shop to change the piston color and trigger the associated achievement. Tips for Efficient Progression
Unlock the achievement once, then dismantle your trap. Or rebuild it as a harmless "jail" with an escape button. lovely craft piston trap achievement guide work
Example: If the plate is on stone, use stone pressure plate to avoid activating by small mobs, or wood plate to allow mob activation. Purchase black ink from the shop to change