Pixelblocks consist entirely of a single size and shape of building block, unlike Legos; the smallest block is about 3/8 inch, slightly larger than the smallest Lego. The blocks join top to bottom with pegs that allow rotation, and solidly interlock side-to-side.

The translucent plastic glows like gems in the sunlight. The Pixelblocks web site provides a free interactive service that digitizes your photographs, so that you can build them, as flat pictures, with the pixelblocks. The concept takes the old-fashioned paint-by-number picture a big step further. In my hands, the results onscreen were great for our calico cat, and less wonderful for the face of the boy holding her, as one would predict from the lack of flesh tones among the blocks (except for those few people who happen to be the exact color of root beer). The results include a breakdown of the number of each color required, and which of the very high-priced individual color packets you would have to buy to make your picture. It's more economical to buy a set of all of the colors available, and more fun to just build things.