Good sources/materials for lap cloths?

What's a good source/material for a lap cloth to keep the dulcimer from jumping around?

[As much fun as it is honing my Tai Chi skills while strumming a moving target, I prefer to focus on the music more when I'm sitting down ]. Swearing off polyester pants and elevating my feet a bit makes it functional, and I'll probably wait a while before I invest in a strap or a stand...