A lot of secret doors in Minecraft have at the none secret side of the door visible pistons. I my opinion doesn't that look nice.

So I made one myself. At first I wanted to make a 2x3 door, but powering these pistons the way I wanted it couldn't be done. But than a thought to myself: "It's a secret door, the doorway doesn't need to be big." so I made it 1x2 instead and you can only take a very short peek at one or two pistons when the door opens or closes.