As part of my castle on Sanctuary, I wanted to include secret one way doors. I finally managed to design a circuit that works.
There is a red torch attached to the side of the A block under the other block. The pressure pad near B opens the door by pulling back two blocks from the stone wall, waiting a few ticks then pulling the blocks and the first pistons to the side. Once the player leaves the pad, the circuit waits a few ticks, pushes the pistons and blocks back, then the pistons push the block back into the wall. The player has those few ticks to get through the newly created doorway to the other side of the door.
My problem is that while this just fits in the space I have in my castle, it is a little clumsy. I can cover the B trench and hide most of the circuitry, but when you reach the pressure pad near B, you get to see the pistons. When the blocks are pulled out and to the side, it looks very nice, but not before the circuit is activated. Ideally, I would also like a passageway straight to the doorway, rather than having to turn a corner.
Anyone got any ideas on how I could change this circuit to make it 'nicer'?