This 3-D contact scanner illustrates two principles: first, you really can build anything with Legos; and second, radiation-based imaging is not the only route to 3-D glory.

As the scanner pokes its prey (here, a small, green plastic frog) with a needle-like probe driven by a tiny motor, a light sensor detects contact between probe and object with an accuracy of 30 micrometers, and a linear actuator translates the rotation of the Lego gears into linear distance at a resolution of 6.25 micrometers.

A computer records the resultant three-dimensional coordinate data and uses them to construct a 3-D grayscale model.