What is the strongest and best glue to buy for bonding crafts?

Well, I would use a two-part epoxy to glue the rhinestones to the metal, but the metal has to be slightly scuffed up/sanded under the rhinestone to make a good contact, and I would use contact cement to glue the tablecloth to the metal, and, once again, the metal should be lightly sanded to get some "tooth" to it so that the glue will hold fast.

Good luck!... ☺

A slow-cure two-part epoxy might work, but you would need to scratch both surfaces to increase the surface area. The solvent that keeps the epoxy fluid might melt your plastic as well. The better method might be getting settings that can be swaged or bent around your stones to hold them in place. Silicone adhesive might also work for both of your needs. Silicone holds fish tanks together, so it should hold metal to glass or plastic pretty well.

Don't know if it is available in the UK, but I use E6000.

probably elmers if you dont want anything exspensive gorrila if you want the good stuff