I drink a prodigious amount of seltzer and have been saving the bottle caps since first building memory games. My first games required me to sort through the recycling bins at a school. My friends in the kitchen ran the bottle caps through the dish washer for me.
I sorted the bottle caps into piles of matching caps. In order to construct a difficult memory game, the bottle caps should all match so players cannot memorize what is on the reverse of the caps by the type of cap it is.
The bottle cap is small; portable; and an available, scalable material. For these reasons it is an optimal basis for a game piece.
The students rough cut the icons from the printer paper. They used glue sticks to affix the paper to circles pre-cut for the bottle caps. The paper was then trimmed to fit the manila paper. Using scissors was good for the students because it required hand/eye coordination, fine motor skills, and hand strength.
Building these memory games required far too much hot glue, since the paper was purposefully not cut to fit flush to the bottom of the bottle cap. For this reason it was dangerous for the young students to do the final construction of the games.
As the container where I store my bottle caps approached capacity, I decided it was time to revisit the memory game and revise the design to make up for the shortcomings of the first iteration.
First, I would overcome the hot glue issue by 3D printing coin inserts that fit inside the bottle cap. A small dollop of hot glue would suffice to hold the insert in place.
Not everybody is able to read braille, so while I considered using braille in the design I decided not to for a couple of reasons. First, my 3D printer does not have the resolution necessary to do justice to 3D printed braille. Second, not everybody reads braille, so the letters or numbers on the reverse of the game piece would only be meaningful to those who do.
While I could have just 3D printed tactile memory game pieces by themselves and forgone the bottle caps, I wanted to hide any inconsistencies in the 3D prints that would make a piece identifiable by a player.
The design itself needed to be small enough that the player could feel the design within the cap. However, the design could not be too tall, or the person trying to feel the design would not be able to accurately feel the edges of the design.
I also wanted to create a design that was easily remixable by others who might be more knowledgeable about sight issues, or who wish to expand on the design.
I used digital calipers to measure the small internal ring of the bottle cap. I also measured the interior diameter of the cap.
I used Tinkercad to design the model of the insert. My design accounted for the shrinkage that occurs in the ABS plastic I use as well as the actual print size that emerges from the printer.
It took three iterations to determine the optimal height of the design. Early designs were 10 mm tall, which prevented the bottle cap from sitting completely flush when turned over. 8 mm proved to be the ideal height inside this particular type of bottle cap. At this height the design fit in the bottle cap in a way that made it easy to determine whether the bottle cap was oriented up or down, too.
I determined the optimal size of the design itself is 15 mm wide and 2 mm tall from the insert. The object is visually apparent, fits inside the cap, and can be easily felt by the player because there is enough room around the design and the rim of the bottle cap to be able to discern the edge of the design with one's fingertip.
I used the primitive geometric shapes in Tinkercad to design five of the six starter pieces. The sixth piece, a mustache, was designed using a community shape in Tinkercad.
The game can be adapted for play by sighted players and players with sight limitations by putting the pieces in a muffin tin.