Cheap and environmentally friendly enough for even the hippies!
For this instructable I'll be using a bit of my own pink hemp (three cheers for extra hair dye!), though any type of string will work, even paracord. =)
Step 1: Materials
Hemp (or another type of string - floss works great but the result is much thinner)
Something to cut it with
How much? Well, as for beads, probably less than five if they're big enough. Maybe 10 if they're small. It doesn't take many.
Step 2: Cutting and starting
The two middle strands should both be a little over twice the length of your wrist. To get them both the same healthy length, cut a piece about 5 times the size of your wrist in half.
The outside strands should each be about double the length of the inside strand. You may want to give a little more string just to be careful. As most hemp rolls are not the same gauge, or thickness, most will require a different length for the outside strings.
Once you have the four strings cut, align them so that the long strings are on the outside and the short ones are in the inside. Then, tie the string in a loop by first making a loop and then tying the string onto itself. See pictures for demonstration.
Naturally, if you do not like this method of tying a loop, you can tie it some other way!