how to make a simple trap in mc

THIS IS BASED ON TNT RUN
1.dig 1 block wide hole really far from surface

2.put a tnt on the 2nd block from surface

3.then put a sand/gravel on top of the tnt

4.then put a pressure plate on top of the sand

5.finaly get a sign and write something good in it

THERE WE GO YOU'RE TRAP EASY PEEZY LEMON SQUISY :D