What it says on the title;)

If you want its possible to replace the blocks to something of your choice

NOTE:
The input for the device must be placed at the left of the creation. So lets say your facing towards were the doors open, the pistons to the left must be powered first.

Additional Notes

Its possible to add 2 levers one on the inside and one at the front.

Gates like a XNOR GATE may be useful

If you want you can add a T-flip-flop via button instead of using a lever