This is my first tarp, so I thought I would show it off and see what *polite* suggestions and criticisms everybody might have to offer;-) I will admit that I have some small experience with the sewing machine and making homemade equipment, and I have already made four gathered-end hammocks (three of them with bugnets and two of them with Hennessy-style velcro bottom entry).
This is the "winter tarp" from the Backwoods Daydreamer design.
The tarp is made from "bargain" fabric ($1/yd) that appears to be polyester and is (so far) totally waterproof. I have it set up tonight for more storm testing.
The ends have velcro to keep the doors closed. I think that I will add a snap or something at the bottom help keep the doors closed (although they have not offered to come apart yet).
I made some seam sealer from silicone and mineral spirits and applied liberally. The reinforcements are ripstop nylon, and the tie-outs are grosgrain (except for the webbing I used on the pullouts). I am afraid that the grosgrain might not be stout enough, but we will see.