Bottle Top Snakes - even without all the other stuff as a cheap threading activity for fine motor skills this would be a great idea. I personally use pipe cleaners to thread things onto like beads, but lids would work just as well
buy a cheap drink tray, layer with different and unique beer bottle caps, then cover in resin or epoxy! can paint the bottle caps. maybe spray paint silver or something then make them the bottom of a tray that holds stuff for the centerpieces?