I would say the easiest thing to build a forklift with is 8020.
www.8020.net
This depends on how much equipment/resources you have build with.
If you do a forklift you definitely need to use a motor to move it up and down.
You can use either cable, chain, or a rack & pinion to move it up and down.
You will also need 3 stages to obtain the height you need to reach the center tetra.