Butterfly Dice Cup
A butterfly dice cup is a mechanically-gaffed dice cup, used to switch loaded dice in and out of play, in various gambling dice games, where dice cups are commonly used. Butterfly cups are very sought after by collectors of gambling paraphernalia and are nowadays also very hard to find.
The butterfly cup shown on this photo is one of the very few that come form the very first set ever made. This particular cup is accompanied by all the original paperwork, as well as a matching fair cup.
The butterfly cup in this photo is quite historic. Not only was it one of the first sets made by the actual inventor, but it was also the actual set that had originally been purchased by Carl Stahl (as seen from the original bill of sales accompanying the set; see enlargement below). Carl Stahl was the owner of the infamous Hunt & Co - one of the leading crooked gambling suppliers of the 20th century. This particular set was his personal sample set that he had purchased directly form the inventor, just to decide if he wanted to carry these cups in his store.
As mentioned earlier butterfly cups are very hard to come by, these days. Also, at this time they are no longer fabricated. The reason why they are no longer made is quite interesting and may sound quite surprising, at first.
The mechanics of a butterfly cup are quite intricate. To operate the cup, the operator must first press a secret button (hidden below the layer of soft leather) on the rim of the cup. Once the button is pressed, the operator can give the entire base of the cup a slight turn. This turning action changes the position of a hidden flap, at the very bottom of the cup. The cup basically has two chambers and by twisting the cup (i.e. changing the position of the flap) the operator is activating one chamber while disabling the other.
What is fairly unknown is the fact that the actual mechanical apparatus of these cups has never been fabricated by the maker(s) of butterfly cups. The intricate mechanical contraption is part of an engine of an old airplane. These airplanes are no longer made and the surplus of these particular airplane engine parts have been exhausted, quite possibly for the production of butterfly cups.
Below is a photo that offers a rare (but partial) glimpse into the details of mechanical contraption that was originally built for an airplane engine and ended up on a piece of crooked gambling equipment. Note the button at the side of the cylinder. Also, not the glue residue at the back of the cylinder. This glue dried up throughout the years and the back cover spontaneously loosened up, which made it possible to remove it and exposed part of the mechanics. Otherwise this butterfly cup is in near mint condition and fully functional. Since this cup is not currently used for gambling (or better say, for cheating) it seems a good idea to leave the back unglued so that anyone wishing to study the mechanics of the cup can have a closer look, without damaging anything.
Naturally, it would be quite possible to copy the mechanics of the apparatus and make new butterfly cups from scratch, but for some reason no one has taken this task, as of yet.