I'm going to try and find one of my links to DIY or HGTV for making shakers after work today. In the meantime....I like to use Fun Foam in mine. I cut out the shape with my Sizzix or Coluzzle and run it through my Xyron (510)twice (once on each side) I broke my 500 doing this, so I wouldn't recommend using the 500. I use sheet protectors, transparencies, overheads. If you are in the Everything Else swap, you'll be getting shakers made this way.
I've tried using double stick tape (I found mine at Michaels), too, but I wasn't good at getting the corners perfectly butted up to each other and had trouble with leaking.
I'll be back later with the link.
Jeanne