The disks reference a schematic file made by MCEdit, binvox, etc. When right-clicked onto a building guide the guide will show a ghost image of the non-air blocks in the schematic with the building guide at the center of the base layer.

The blank disks are placed in a schematic stamper that has a list of available schematics available. The schematic files would be located in the /mods/resources/OpenBlocks section of the base .minecraft folder.

This could work in conjunction with the guide transform in my previous issue.