I made a big one for my garden. It is like a that scene in honey i shrunk the kids with Rick Moranis laying in that cantilevered flying cot thing but i use 2 high speed winches and some machined aluminum and the cabling sort of like an etch a sketch controls. I control it with the same usb gamepad that titanic sub imploded with. i can raise and lower myself about 4 feet to get inbetween the rows. It is pretty fun to play in too. I want to build a robot to get in it and then remotely control the whole thing. Its basically the same thing as the NFL spider cam but holds more because I'm a fatass and performs much worse. I used 12 foot 4x4s with concrete bases. Its about a 20 feet by 35 feet garden. My only real concern is the longevity of the cables, the hight im suspended at isn't really dangerous but i know i am not using the right cables for the winch. 3/16 in marine grade vinyl coated 4200 pound working load limit. my spools or whatever you want to call it is 6 inches im afraid theres too much tension on parts sometimes. I had an alternate design that used water as a ballast and you just pump or drain water to move around the grid but that was too ambitious for my lazy ass.