(Spray paint the jar lids on the bottom and inside. Mosaic tiles and resin to seal. ) CFDS Mosaic Cocktail Coasters made with jar lids, tiles and resin. Great instructions and can make it say anything you want
DIY Glitter Magnets - an easy craft idea for kids too. J in the Library's note: Though glitter is almost guaranteed to be messy, this is a relatively easy project that would only take 2 library classes, or 2 meetings of a maker club.
"Cover rocks with mirrors and they look like melted disco balls." I don't think these are rocks but if you could find a "melted" looking rock you could cover it it pieces of mirror or CD's to create a "Melted Disco Ball".
Turn Tiles into Coasters by Stamping them with Paint! Have some Christmas stamps? Get some inexpensive tiles. Probably after they are thoroughly dried would be smart to give a couple coats of a clear sealer, so ink lasts.