I own shelters that weigh less than one pound, and for summertime weather in the Sierra Nevada, I generally don't need to plan for weeks of continuous rain. A brief rain shower is common, so I always sleep in some kind of tarp-shelter. My current favorite ready-made shelter is a Gossamer Gear SpinnShelter. With netting mods, mine runs around 10-11 ounces for the soft pieces, plus poles and stakes. I value the way that it can be storm pitched down to the ground, as necessary. I spent two weeks in the rain in Alaska with it, so I know how that works.
However, I am interested in sewing my own shelter now. My goal is a shelter that weighs a bit less than what I have now. I have some yardage ordered up, something of a similar weight as spinnaker fabric. I recognize that it may not have 100% waterproofness, but it may be close. Not quite cuben fiber.
I've surveyed the general design choices, and what I try to cook up now may be a blend of several designs. I've seen the Jay Ham SUL tarp design. I like the SpinnShelter, although it is much longer than what I need. Flying Wedge. SMD Night Wing. Oware Cattarp. GoLite Lair. If I had no other input, I would attempt to make something like the SpinnShelter, except a lot shorter and a bit narrower. It will likely be like a flat tarp, only more shaped.
Any suggestions out there?