I don't, but I will definitely check in to it, thanks for the heads-up. I've seen it mentioned before and keep forgetting to check it out.
I think about the dream of copper foil stamping due to the Exquisite Bold (EPCC) gold stamping experiment recently. I'd love to win the lottery just to produce some freakishly high end collector decks at reasonable prices, when money isn't an object and I don't need the profit. That would be fun!
In the meantime, I'll just look at my copper Rarebits and dream "what if?"!
Just curious...is there a realistic copper (at least more so than what's shown above) in the realm of printing that may not be being used due to expense, or is this copper as good as it gets with current technology/chemistry? It's a bit different with me as a collector. Since many of my cards never leave their tucks, the tuck has far more weight in my purchase decision than back color. These are great for me as a collector because I have the copper foil that I love so much whereas a lot of folks are disappointed in the back color, which I understand.
I mentioned the Synthesis deck because at the time I mentioned it, Albino Dragon was still having a nice sale on damn near everything. And it's shiny and coppery, too!
As far as foil, you can see that copper is possible - it's just not as popular. While the price of copper's gone up in recent years, given a choice between pennies-per-pound copper and the more expensive silver and gold, most deck makers opt for the silver or the gold. I don't know if there are copper metallic inks for printing, but again, since it wouldn't be as "deluxe" or as shiny, even if it's out there it's passed over most of the time by the more precious metals.
The 52 Plus Joker deck has foil on a large area of the backs of each card - the silver deck with slipcover sold for $45. There's a gold one in a simpler box coming soon from CARC via Expert. This will be likely be one of those odd cases, just like in the military, where silver is more valued than gold! (When comparing US commissioned officer rank pins that are identical except for color, the silver one is higher-ranked than the gold one by one pay grade.)
Fun Trivia about copper and copper coinage...
The rising cost of copper reached the point in the late 1970s/early 1980s where a single penny contained barely more than $0.01 worth of copper (largely due to inflation), so in 1982 the US Mint started using a zinc core with a thin copper coating for a total copper content of only 2.5%, except for a small commemorative run in 2009 for Abraham Lincoln's 200th birthday. You can tell the difference between them by weight (zinc is heavier) and sound (copper coins make a high-pitched ring when dropped on a hard surface, while zinc pennies make more of a "clunk" sound).
Before zinc was chosen, a limited test run of over 1.5 million pennies were struck but never circulated in the early 1970s, all made with an aluminum core, as the US Mint was already aware that rising copper costs would create the need for a substitute. The aluminum pennies were rejected for two reasons. First, they were prone to causing mechanical problems in the vending machines of that era. Second, if swallowed or lodged in an airway, the metal was difficult to detect using X-ray machines due to having a similar radiodensity to human gastrointestinal and respiratory tissues. The pennies were destroyed, except for one single coin which was donated to the Smithsonian Institute.
While it is illegal to destroy US currency and coinage, many people still do melt down older pennies to sell for the copper content to a recycling plant, as well as copper wires stolen from street lighting systems, railroad yards and anywhere else that it's not under guard. Unfortunately, it's still the cheapest viable metal to use safely in electrical wiring - cheaper alternatives are either poor conductors or liable to melt or burn when carrying a strong electrical load high in amperage.
Circulating copper and copper-coated coins are also the best breeding ground for viruses and germs transmissible via touch or fluids, which is why you should always wash your hands after handling money, especially before you touch your face or your food.
Lastly, in the early 1940s, copper pennies were replaced by zinc-plated steel for a brief period as the copper was in high demand by the US military in World War II. These coins bear dates ranging between 1942-1944, though none were struck in steel before 1943.