The sleaves store 2 disks in a pancake. 110 are required for the Heroine 220 tower. The most economical way to make sleaves was to make them out of a single piece of black paper.
A combination of laser printing and the Sharpie MAGNUM color them black. It's the only practical use ever for the Sharpie MAGNUM.
We discovered after 8 years of optical disk archiving that ambient light of any kind destroys recordable optical disks. It reacts with their chemicals just like the laser that originally burned them, just slower. The black sleaves reduce the degradation in addition to protecting them from robot glitches.
Every detail of the sleave was highly optimized for accesses by the robot and for minimum cost. The corners are beveled to prevent jamming on the tower walls. The paper is colored black to conceil it from the robot's position sensor. The glue flap faces down to prevent jamming of the grabbing mechanism. The paper is folded perpendicular to the direction of motion in and out of the tower to prevent splitting between two rows.
To cut costs, it helps to know someone with a laser printer to print the sleave patterns. Since toner cracks when it is folded, the Sharpie MAGNUM fills in the leading edge after folding. To cut down on insanity, they're only made 5 at a time as needed.