Like Leo, I use coffee grounds with CA glue. Have filled really big
voids--one about 2.5" by 1" and it looked great. It became the main
feature of the vase. I put a piece of tape on the back side of the
hole, and just alternated grounds, CA, and accelerator until I filled
the void. I've used both used grounds and new--doesn't seem to make a
difference.
Earl