We had an old metal garden table and chairs rusting in the corner of the garage. They had circular insets containing ceramic disc tiles that weren't terribly inspiring.
Removing the ceramic tiles wasn't a great challenge, and the table and chairs looked much better for a coat of white Hammerite.
To replace the ceramic tiles I made up two discs for each: one in plain mirror glass (sealed with varnish to keep the damp away from the silvering), and one in a coloured English Miffle pattern. The mirror reflects the light back through the muffle pattern, giving a sparkling finish that will stand out wherever the furniture is in the garden.