The mod on the lift
for Minecraft PE 0.12.1 and 0.11.1 called Elevator Block
. With it, you can in any place where you will need to install the Elevator and use it to climb to the top or sink to the bottom. Now the high walls and steep slopes will not be a problem for you, at any point you can 2 or more blocks on top of each other (maximum 16 units) , jump on the first block of the Elevator, then press down (Down) in the lower right corner and you'll skip to the next block or to the floor.
If you are tired to find ways to go down in the game Pocket Edition then this mod will save you from this problem and you can easily go down to the bottom without wasting time and health.