this is a classic hidden door in minecraft, and it's a great way to hide all your stuff from other players. I am going to show you how to make it! :)

Step 1: Step 1: Make Your Wall

make a wall that's about 4*4 blocks high wall so you can hide your redstone stuff.

Step 2: Step 2: Piston

put some pistons in the wall.

put the blocks that's the same to the wall in the pistons. and do the redstone like what I did on the photo.

right click on the repeater for one time.

hide your switch and you are done!!!!!