I designed the box in the Tinkercad software and 3D printed it in solid white plastic. After several tries, I laser cut a correctly sized piece of mirror for placement in the box. I then experimented with different interior fabrics and papers until I came up with the black walls with gold stripes. The illusion of emptiness looks great even at that small size. Lastly, I decorated the exterior of the box with patterned paper and a white bead on top.
I can now postulate that at roughly one inch square, this is most likely the smallest mirror box in the world. Under the lights of the Suitcase of Wonders miniature magic theater, the tiny mirror box looks terrific. It is a welcome addition to the revised Marie Antoinette-themed illusion piece that will have its debut sometime soon.
With how well the mirror box turned out, I am contemplating building a miniature Proteus cabinet next, using modified dollhouse furniture and lighting.