(x-post. it seemed appropriate for here)
Just discovered this and thought I'd share for those who may find themselves in a bit of a playalicious playwear emergency requiring a bit of style MacGyver-ing. I'm admittedly particularly proud of this. ;)

So I'm at a friend's house helping her pack for the burn. She has 2 cu-ute dresses that she wants shortened because at knee length they're too "demure" and not enough fun and funky. The problem of course is not only that you know, it's totally last minute, but that she's in the process of moving... like, as we speak. Literally. We had just finished carrying 95% of her belongings in boxes in the new apartment. So no ruler, no tape measure, no pins, no cutting board, no rotary cutter, no chalk pencils, no pens and certainly no sewing machine. Fortunately she had some decent scissors (for paper cutting, but sharp).

HOW TO SHORTEN A SKIRT WITH A BAR OF SOAP AND A PIECE OF PAPER:

I found a small bar of soap in the bathroom and a random piece of paper on the floor. The edge of the soap marked cleanly on the back of the fabric to substitute as chalk. And it's soap, so it's not like it'll make the dress dirty or cause a stain. ;) It can be washed out later.

The paper served as a substitute ruler. She wanted 6 inches off the bottom. Folding an 8.5 x 11" piece of paper in half widthwise gives a measuring tool of 5.5". Eyeball another half an inch and refold, and there's the 6" length. (btw, double that and you have a foot long ruler if needed.)

I just laid the folded 6" long paper at the bottom of the hem and marked the top with the soap, making a line for the new hem all around the skirt. Then carefully cut along the soap line. It worked great. One skirt was vinyl so it didn't need to be stitched (she could fold it under and glue it if desired). The other could be staystiched on the ride up or when she returned, leaving the bottom edges with cool fraying like jeans.

I figure this kind of solution could easily be done on-playa if needed. :)