Another idea for the bowls: maybe a bird feeder of sorts. They could hold seeds, you could stack them up alternating on Christmas tree shaped wire or wooden frame, or along a single row. You could put little dowels out for the birds to perch on.
Or maybe fasten them to a small square base and use them in your cars center console to hold quarters for parking meters. You could glue the top of the pipe to the square wooden base, and saw off the bottom of the pipe with the broken stem. It would probably hold about 2 bucks of quarters.