so i saved a bunch of pennies, made a template, bought some mesh backing for mosaic tiles, glue that could hold metal and started making sheets of tile.
then we just installed them directly over the existing ceramic tile in the vestibule with regular thin set.
and then grouted it with laticrete epoxy grout in chocolate truffle.
it was really very easy and i love the way it came out.. most people that first see it don't realize that it's pennies. i like the blend of the different shades of copper that was created from using old wheat pennies right up to bright 2010 pennies. oh and in case you want to know... it took 3,889 pennies (it's about 3'-8" x 5'-8"). so $38.89 for app. 24 sf of tile is not bad at all.