Many powders available are 'metallic', and suspend in the epoxy creating interesting patterns and effects. All the rage right now, just one more thing I should have kept up with when I did it years ago.
IF you're going to try the 5 minute epoxy you probably should count on it starting to set in 3 minutes. AND, unless you're buying the 5 minute epoxy already colored you're probably going to be out of luck. IF you find a two-part 5 minute epoxy you're still going to lose a couple of minutes making sure that it has been mixed thoroughly. BEWARE!