You dont mention what stitch type you're using. Personally I'd do a running stitch, perhaps 3.0mm (longer than usual) and a double run (so the same line stitches twice) rather than a satin (zigzag) stitch. I remembered your question while digitising tonight :) (my internet was down and I was bored lol)
You hide little trinkets and little toys etc in the bags but the bulk of the filling is poly pellets which are used to fill soft toys (like beanie bears) and dolls. The ones I have used look similar to dried split peas, except that they're an off-white colour and not edible. In fact you could maybe use dried split peas .. hrm, now there's an idea lol.
hth :) xXx
thanks so much. i'm still working with it. i'll give that a try. the design i'm using has a satin stitch for the finish on the little vinyl window.
ok, i have found all the answers except...why does the vinyl keep popping out like tear-away stablizer!