Imagine a desktop fabricator capable of making perfectly repeatable, arbitrary, multi material 3D objects with microscale precision. The objects would be composed of millions or even billions of small physical building blocks (voxels). Some building blocks could be hard, some could be soft. Some could be red, others green or blue. Some could be conductive and others could perform computation or store energy. Some could even be sensors and others actuators, and so on and so forth. With a relatively small repertoire of building block types and a rapid assembler, one could assemble a relatively large variety of machines at high resolution. How would that work?