Three blocks high piston elevator

I did not improved this one much after I made it for the first time, but it does work. The problem is that I had to cope with was that extended pistons can't be puled back by sticky pistons and sticky pistons pull back only one block. This is also the reason that I used sand, to make it less complicated. To lower the elevator (a 2 by 2 blocks platform) it needs a lot more complicated signal which is difficult to create with logical gates so I used a very useful technique for a memory cell which can be seen at the end of this YouTube video. For the elevator to go up press the left button and for going down press the right button. If you would press the wrong button at the wrong time it will cause the memory cell to get out of sink with the elevator itself. So it is far from perfect, but the main idea works. Maybe in the future I might improve it (one button input and toggle up and down) and make it even higher.

But I mainly want to show you how useful, handy, clever and so forth this memory technique is. Because this why you are able to do much more complicated actions.