They said that by using stereolithography, their printer could offer "layer thicknesses and feature sizes that are worlds ahead of what is possible with" the existing technique used by budget printers, which melt plastic and squeeze it through a nozzle to build up each layer of an object.
Some experts have commented that Angel Ambush was not 'real' augmented reality at all, because the virtual angel was just a layer of video manipulated by a human operator, rather than an independent 3D object.