This is the backpack unit that mates with the disc from TRON Legacy. The disc is http://www.thingiverse.com/thing:1032216. Magnets are used to make the disc stick to the base, but can be removed with a gentle tug.
Print one cap, then print either the unified body or the four quadrants with mirroring. Glue them all together, patch cracks, sand, paint. Finally install round magnets 1/4" across and 1/16" thick into the provided holes on both the base and the disc. Make sure the polarities are correct to snap the units together. Super-glue works very well to hold the magnets in place.