I don't believe we need a whole category on the subject, but a thread on DYI thong making is quite appropriate.  Most of the time it is simpler for people to purchase a thong rather than make them.  I have some sewing skills, a machine or two and a good 4 thread Singer serger.  I also have box with a selection of cones of both standard and fuzzy elastic threads in various colors. 
I find it good to have the skills and tools for the occasional modification, for example taking the extra out of a front seam of a pouch when it has too much room and is too floppy, or shorting a back strap, but a good thong has elastic in the edges which I find is beyond me to get right. It is difficult enough handling the stretchy fabrics without having to correctly tension and feed the edging elastic at the same time.
You may want to check skinzwear's listing on ebay for off cuts of spandex fabric.  They almost always have listings where they are selling off the end of a bolt a couple of yards at a time.