I did a series of tarp configurations for my channel at YouTube:
I've embedded them here for your viewing convenience.
The first two videos use a 10 x 12 flat tarp. You can also use smaller tarps with these configurations. Of course, there are a myriad of other pitches, but these two seem to be the favorites.
If you get a 2-3 yard swatch (54 inches wide is the usual bolt width) and secure it to the tart with clamps or ball and line tie downs, you'll have a decent versatile shelter for under a $100 bucks. The silnylon ones weight about 20 ounces, with the netting, guy lines and some stakes, you'll have sleeping for two for under two pounds.
Ultralight tarps are easy to sew or buy them at Campmor. I saw a guy with the polyurethane walmart one on the Long Trail in Vermont. You can use tyvek also, which is 9 foot widths, by hand sewing or adding grommets for staking points.
Another popular option for the larger flat tarp, which does not need any hiking poles for support.
This is a very popular option for two people, who bring a ground sheet and use the full width to create the canopy.
I was sent a Brooks-Range 5 x 8 tarp to test. I came up with 5 pitches, ranging from shade to sleep quarters. A handy size tarp, especially if you wear a poncho or use a bivy, as a back up plan in extreme weather.
These configurations utilize extra cordage to create more floor space.
You can make your own 5 x 8 or longer tarp by buying 3-4 yard piece of silnylon and either hemming it to include staking loops, installing grommets, or utilizing the ball and loop (dead man) approach.
When chosing your shelter for a long hike, consider the weight, cost, set up time, and space.
Many people think a tarp would work for them, but find later that it doesn't offer the critter barrier they would like. Yet, sleeping in an Appalachian Trail shelter is more open, so by comparison, its fairly private.
Never do a long hike without a shelter. I've met people who thought they'd count on shelter floor space and had to crowd in with another, sleep under the shelter in the dirt or under a picnic table. Still others have just donned their rain gear and sat it out. Not fun.
There are many cottage industries that do ultralight shelters and tent like structures. Check out used gear if you're on a budget, either through e-bay or online hiker forums.
Check out :
for a search started on used ultralight backpacking gear.
Even Granny Gatewood had a shower curtain.