As Pat mentioned, clear vinyl shower curtain works great. Then get the wet erase markers from an office supply store. Personally, I am not at all crazy about the technique. I prefer to draw out my block design on paper then use tracing paper to audition motifs. If I come up with something I really like it goes into my portfolio of quilting ideas and I can do it from the comfort of my sofa without having the quilt there. Finally I am not risking the quilt at all by accidentally marking it.

Joanns in the longarm section

Walmart carries clear vinyl in different weights in the fabric dept. on rolls.

For blocks I use the plastic sheets that you use for binding reports and a dry erase pen. I get them pretty inexpensively from Staples and they hold up well. I would like to try the roll from Joann so that I can audition a larger design but so far the smaller sheets have worked well for me.

i think this would make a mess...at least for me! heck, i can't even get it stretched out to go over the bowl!

if you decide to use a permanent marking pen, like sharpie, it will come off with alcohol, because the marker itself is alcohol-based. don't use other permanent markers that are solvent-based. the solvent you must use to remove the ink will probably cloud the clear whatever-you-use, and it is way stinkier than sharpies. all-in-all, i would go with the dry erase markers. just be careful not to slip off the side no matter what kind of writing instrument you use!

You can get that heavy clear plastic at Jo ann's. I use it for my over lays when I do Hand Applique.

I have used freezer paper to preview patterns on my longarm - it is almost see through enough and you can write on the dull side with a sharpie and it does not bleed through onto the quilt. Once I got the pattern I wanted, I put it on the back and used it like a pantograph. It's cheap!

It sounds like sheets of clear mylar which come in various sizes but start as small as note book paper. I get mine at a teahers store

It is called Quilters Preview Paper. You can purchase it at Handiquilter.com.