marshmallows work good, you may have to experiment with the various sizes of marshmallows a bit to find the ones that work best for you application. definitely don't use the dehydrated kind that come in popular children's cereals though.
I use welders glue and put a few down, then strap it in with a rubber band. Theres a point the camera shakes to where it's strapped to too tight and lets jello in.
