I have used the square hole punch and would suggest the SU beads for size if it is a small window. Don't forget you can use the punch repeatedly and get a bigger window! That's what I did with this card:
Gallery at Splitcoaststampers
Instead of foam tape you can use laong rubber scraps, like from trimming background stamps. Peel off the red rubber and place it down, then it is easy to pull off the paper when you are ready to adhere. It is also easier to cut as my scissors got VERY gummy with foam tape, but seem to do very well with the rubber strips.
I also did "faker shaker" cards at a workshop with tiny ziploc bags and the square hole punch. We added coffee and adhered the small bags with mono, but I'm sure the small cellophane bags would work as well. This was an awesome card as a make and take b/c it looked a lot harder to make than it was, and even beginners could do it (we did not do the foam marshmallows at the workshop).
Gallery at Splitcoaststampers
I did shaker cards with my downline, and it took quite a while. If you were doing it at a workshop, I would try a faker shaker without the foam tape and mounting unless it is a small group with lots of experience. My gals loved it, and I sold lots of square hole punches. Even though it is hard to see in the scan, the greeting can be seen through the sqaure hole punch, which they thought was awesome. Goodl uck!