Here is the pattern for my poncho/shelter which I promised some time ago. When we first made this (back in 2000 – for my first ‘moose hunting’ trip to Supper Cove, Fiordland) there was no such thing as a waterproof zip. As you can see we used 2 oz ripstop and Velcro. Della made three of them in such a way that they two or three could be combined to make a bigger (and bigger) shelter by joining them edge to edge (which I still think is a good idea if you sometimes tramp with friends).
Now that there ARE waterproof zippers (eg here: http://www.zpacks.com/materials.shtml scroll down – 13 grams and US$4.78 per metre) you can make a far more waterproof poncho using (probably) 1.3 oz/yd2 ‘silnylon’ (eg from here: http://www.questoutfitters.com/coated.html#SILNYLON%201.1%20OZ%20RIPSTOP ) – US$10.49/yd = 2.5 needed) OR .51oz/yd2 cuben fibre from either of the above if you want it ultralight. (NB zpacks have .67 oz/yd2 cuben avail. In camo!) In silnylon it will weigh a little over 150 grams; in cuben it will weigh less than half that – about 65 grams! That is a SERIOUSLY lightweight raincoat AND tent! You would make the tie-outs out of Grosgrain ribbon (available from both of the above).
You can see how to wear it as a hooded/hoodless poncho in the pix, and how to pitch it as a shelter here: http://www.theultralighthiker.com/pitching-the-poncho-warning-this-may-save-your-life/
Instructions: Feel free to make ONE yourself, but (as with my other patterns) if you are going to manufacture them for profit, I would appreciate something in return! Cut the material to size. Hem all around. Sew zippers to close AB to AC, BD to DF & CE to EG (leaving openings of the approximate size shown. You might run a thread around inside the hem of the ‘hood’ with a drawstring/s, having left an approx 1 cm gap in your hem stitching at each side for that purpose, so that it can be closed tight around the face. Sew (approx 1” – 25mm) grosgrain tie outs on all four corners and half way along each of the long sides. NB: If you form the grosgrain loop with one end sewn to one side of the material and the other end to the other side with an 180 degree ‘twist’ in the middle it will be easier to peg out.
You will notice I have included an optional 2′ (60cm) fabric extension (dotted lines) which will allow the poncho to become a 7′ x 7′ tarp. In this format it can be slung diagonally between two trees to form a hammock tarp, or slanting downwards at 45 degrees to make an excellent 10′ deep shelter – as shown here: http://www.zpacks.com/large_image.shtml?shelter/tarps/diamond_tarp_l.jpg
Another option is to make the poncho out of Tyvek and configure it (for three purposes) like this: http://www.theultralighthiker.com/tyvek-bivi/
If you find these directions a little difficult, try making the poncho out of a space blanket with sticky tape as illustrated here:
NB: Click on plans to enlarge: