Most gamers are content to hunt up the coolest looking dice sets around and use them to slay dragons without worrying about the process that goes into the manufacture of the dice.
But for the more curious gamers out there we thought it’d be nice to go over exactly how dice are made.
It’s worth noting before we go into detail that there are different manufacturing processes for different kinds of dice. Even within the world of standard mass-produced plastic dice there are variations. We’re focusing here on your standard D&D dice, which covers just about any gaming dice. We’ll also touch on variations in the manufacturing process that are used for casino dice.
How Dice are Made: Raw Materials
Modern gaming dice are made through the plastic injection molding process. This starts by identifying the ideal plastic to use for dice of the thousands of different kinds of plastics that have been developed for plastic injection molding.
Dice need to be made from a hard plastic with good impact strength that can easily be colored. This leads most dice to be manufactured with one of the many thermoset plastic polymer. Most thermoset polymers are perfectly colorless, which means that pigments or dyes have to be added to the polymer to obtain the desired color for the finished dice. This can be either an opaque or translucent substance, and for many dice a combination of pigments are deliberately imperfectly mixed to create a swirl or other combination of colors.
In addition to the coloring, various other ingredients are added to the polymer, including a pasticizer and other substances to alter the physical properties of the dice.
In addition to the raw plastic, it is also necessary to create a mold for the dice. The mold is a 2-piece construction made of aluminum or steel that will determine the actual shape of the finished dice. Thus a mold for a simple six-sided die would be a cube (or two halves of a cube). The pips or numbering for the dice are actually a part of the mold itself and appear as extrusions in the mold (which then result in indentations in the dice). The molds themselves are typically made through CNC machining process, where computer models run the machines to shape the metal, and includes draft walls to allow for ejection of the completed part.
The Dice Making Process
The actual manufacturing process starts with beads or pellets of finished plastic — these pellets include the polymer, the colorants, and all additional chemicals. These pellets are the exact same finished substance that the dice will be.
The plastic pellets are put into a hopper that feeds into the injection molding screw plunger — this is essentially a screw that sits within a cylindrical chamber. The screw forces the pellets through the chamber, and as they move through they are heated until they melt into raw plastic.
This plastic is then forced into the closed mold. The mold is kept cool so that the plastic hardens almost as soon as it enters the mold. The mold is then opened, releasing the dice onto a conveyor that moves them along to the next station while the mold is closed once more to allow new plastic.
While basic dice can be made with just one screw operating to force plastic into the mold, some dice are made by forcing two different kinds of plastic from two different screws into the same mold, creating dice that are a combination of two or more completely separated colors. The Chessex Gemini dice are a perfect example of this process.
Once the dice have left the mold they are cleaned to remove trace elements and imperfections and then move onto printing where the indentations for the pips or numbering are printed in an appropriate color. The actual printing process involved covering the entire surface of the dice with paint, so that the entire die is painted the color of the numbering. Then when the paint dries the dice go into a tumbler (like a rock polisher) with a coarse material. The friction of the polishing material against the surface of the dice scrapes off all of the paint; however, the indented areas are not scraped off and retain their numbering.
The dice are then put through a second polishing operation with a finer polishing agent to remove scratches caused by the paint removal and generally enhance the polish and luster of the dice. This tumbling process that most gaming dice go through causes the slightly rounded edges you see on standard gaming dice, which wears the surfaces and the edges unevenly. Technically the dice will roll less true as a result, though no actual physical testing has found the dice randomness to be beyond the normal distribution of probability.
Dice that are used in casinos are manufactured very differently. They are actually machined, rather than molded, within incredibly tight federally mandated tolerances. Dice that are molded are simply never going to be as perfectly evenly distributed as dice that are precisely computer machined — but you and I will never, ever know the difference.
The holes for pips are actually drilled into the dice, and then filled in with a colored substance that is the exact same density as the plastic of the dice, ensuring that there is no difference in weight from one side to another (in theory using indentations for pips would cause the “6″ side to weight less than the “1″ side, though this is a miniscule difference and isn’t a concern for most RPG gaming dice, which use numbers instead of pips).