I cut a sponge to fit the container, and just poured glue in. Students can just tap their shapes on the top of the sponge for a thin, even coat of glue - no more puddles! I worried about the sponges getting icky, but I still have the ones that I made well over a year ago, and the sponges are still intact AND the glue isn't stinky :)
Love, love, love my glue sponge containers.
****Welcome Pinterest-ers :) I wanted to add a quick note about shapes getting mangled/crumpled - as long as the sponge is well-saturated, kids shouldn't have to push them down hard on the sponge, so this shouldn't be a problem - when I see crumply shapes being glued down, it's a clue to me to re-teach students to gently tap the shapes onto the sponge (or that I need to flip or re-load my sponges). Hope this is as big of a life-saver for you as it has been for me!
***** Entering year 3 of my original glue sponges - no mold has set in, or funky smells of any kind! My glue sponges have moved with me to a new school, new set of kids, and new blog - they seem to be adjusting just fine :)