Hammock Tubes (aka HH Snakeskins and JRB Python Skins) are extremely simple to make, and they make setting up and packing up so quick and easy there's no reason NOT to take them.
Some are made from waterproof material...Python Skins and Snakeskins are both made from Silnylon. This protects the hammock and underquilt from water, so you can set up or pack up in the rain without getting your shelter wet. Titanium Hiker even made some with duct tape and garbage bags!
I use Python Skins for my hammock, and a separate pair of non-waterproof skins for my tarp. My favorite homemade ones (for the moment) are made from bug mesh, but I also have two pair made from regular old untreated ripstop nylon. They are very light and allow the tarp to dry (a little bit, anyway) while stored in my pack's outside pocket.
|These tubes measure 2" at the small opening, 5.5" at the big opening, and ended up 57" long due to a sewing error. They weigh 1 oz for the pair.
Um...they're not panty hose.
|Here is the MacCat Standard inside the bugnet tubes.|
|Here is my HH and JRB Nest being swallowed by Python Skins.
Those are homemade skins on the tarp above it.
|There are obviously other ways to do it (like cutting a rectangle, folding it in half and running a seam diagonally, then trimming away the excess), but I find it's easier to cut it first and trim of the end than to try to sew a straight line on the diagonal. That's just me.
JacksRBetter has a DIY page that would work better if you're using silnylon.