Okay, do you really want to make all your own backpacking clothes? More power to you, and good luck. After the first hundred tedious hours of sewing I started buying gear again. However, there are SOME backpacking clothes you can make cheaply and quickly. A few examples follow.
Making Your Own Ski Mask
Find any old thermal underwear top or bottom, preferably made of polypropylene. Cut off a sleeve or leg, pull it over your head, and mark where your eyes and mouth are with a pen or marker. Cut the holes and cut off the extra. You just made a balaclava.
My homemade balaclava weighs less than an ounce. Sew the top shut if you want, or just pin it shut with a safety pin. Making your own backpacking clothes doesn't get much simpler than this.
Put your hands inside a pair of light socks and mark where your fingertips are. Cut five holes in the end of each, and you now have 1-ounce hand warmers that leave your fingers free. Use them under other gloves or mittens in colder weather. When you need to remove your mittens to tie your shoes, you won't totally expose your hands.
A Two-Dollar Insulated Vest
You can buy 1/2" poly batting at any fabric store (I bought mine at Walmart). Unroll it and cut a piece out, roughly two by four feet. Put a hole in it for your head. You'll wear it like a tunic, but under your jacket. It will be among the lightest backpacking clothes you'll own. Mine weighs four ounces.
I took my vest, along with my homemade balaclava, over glaciers, to the top of 20,600-foot Chimborazo, in Ecuador. I also wore it to the top of Mount Shasta in California, and on many other trips. I made it as a disposable vest, but it's held together for years now.
Feel free to contact me with ideas for any simple backpacking clothes or equipment that can be made at home. However, if it can't be explained in a paragraph, it's probably too complex and time consuming for me. I prefer to backpack, not sew.
Steve Gillman is a long-time advocate of lightweight backpacking. Visit his website for tips, photos, gear recommendations, a free book and a new wilderness survival section:
The Ultralight Backpacking Site