I've already done it, here are some tips:
I made a crab net for mine using 3mm hemp cord (12 x 5 meter cords). It's strong as hell. I used a 2" stainless steel ring for the starting point that sits at the bottom. The cordwork for the handles isn't finished yet, so there are still 12 long cords above that I just wrap around my fist and lift her up.
Very strong and sturdy. Plus I tied the net together in zig-zag so that breakage can't spread.
Because it is tied in crab net style, it adapts to any size vessel. I can carry my 5-gal carboy just as easily as I can carry my 6-gal tear-shaped demijohn. And, it's easy to slip on just by tilting the vessel a bit and sliding it under.
It took me about one day of work sitting outside in the sun drinking beer to make it. It makes my carboy look like one of those old glass fishing floats.
