basically i fused 7 layers of white plastic bags together using this tutorial https://www.craftster.org/forum/index.php?topic=178442.0 (thanks jamiewatchthestars!) cut off all the edges and fused the pieces together.
checkbook holder open
i made the strap to go around the holder once and tuck in just under the 2 blue stars (you can't really see it, cause it's white like the background...). it wouldn't really stay closed without it.
here's a few things i learned along the way...
1. you can fuse 6 layers together, but 7 or 8 work better. if i gets too hot, 6 will leave holes.
2. keep the iron moving!
3. you can totally fuse your colored pieces on AFTER you make whatever you're making as long as you can lay your piece flat and iron it under a piece of cardstock. i added all the stars and tree after i'd made the whole holder.
4. the 'fabric' will probably have a bunch of wrinkles and stuff in it when you first fuse it, but if you keep checking it and re-ironing sections, you can make it pretty dang flat and smooth.
5. i used cardstock from an office supply store that i just had laying around to put around the bags. if you need a larger piece of paper you can overlap the cardstock, but just make sure you go back and re-iron where it was overlapped, cause that part won't get enough heat. either that, or just iron in sections!
6. for goodness sake, don't let the iron hit the plastic! i cut my strap off cause i kept going off the paper...
7. how can fuse pockets in by taking a piece of paper the size you want the pocket and letting it hang out one side of the proposed pocket therefore letting the other 3 sides fuse to the base. (hope that wasn't too confusing...)