in the summer me my uncle and my cousin built a large zipline 100 foot long problay supporting over 500 pound 20 foot high. this is not a exact instructions but a guide. it probably cost about 150$ not including wood for a treehouse]
(very old and crappy instructable for reference)
Step 1: Go Build the Tree House
the first thing to do is build a tree house or platform. we built one with a platform sliding door and a little house like thing make it around a sturdy tree. and make sure theres another about 100 feet away
Step 2: Things You Need
large pulley (at first we used to small pulley but they wore out so badly that in a week they were encrusted with marks of the cable)
thick cable ( about 2 or 3 times the thickness of clothes line)
drill and saw and other tools
2 turnbuckles( do not skip this , your ride will suck with oout this )
2 cable thimbles
fastening nylon rop stuff(the stuff you use to fasten down large tents)
rock climbing harness (optional- safety first)
caribner if using a harness
plank of wood
and rope for pulling the carriage up the tree
oh and matreses are essiantal because it hurts to land really hard
Step 3: Carriage
for the carriage use a fastening nylon wide ropey thingy and run that through the middle of the wood plank and connect that to a pulley and i suggest using a fastening buckle for the nylon fastening because you'll want to adjust it
Step 4: Cable Time
first attach the cable to the turnbuckles using a cable fastner or welding or crimping then use some really heavy duty fastening wide thingy stuff and run that a few times around the tree and tie it tie it agaian and put it through the turnbuckle and tie and again. do the same on the other tree.make sure you put the carriage on first though.
Step 5: One More Thing
i use a harness on my zipline. i picked it at moutain eequipment co for 32.00 and use a carabinere to connect it to the carriage . my uncle used to be in the army and he showed me how to make a harness out of rope and s a neat and useful tricki.
Step 6: Go and Have Fun
now go and have fun but make sure to put a matress down and tighten the turnbuckle if theres to much slack.