I saw how a rope hammock is made on some tv special... it takes a specialized machine to properly tighten all of the knots and stuff. Im sure it could be done, but I dunno if you can actually make one that would be safe enough to use.

Step 1 - Go to ebay
Step 2 - Buy a hammock for 20 dollars
Step 3 - Put up hammock and drink a beer

There are a few sites that give instructions...

I suggest going to Mexico & buying one.

I do macrame and I was going to make one. They're really simple. But, the materials were going to cost me $300.00, and probably 200 hours. Can't see the use of this much time & $