A four-motor tracked rover controllable either through an Arduino-based radio transceiver or a standard Lego Power Functions infrared controller.  

Just a simple six-speed gearbox usable in various larger projects. One of the first things I had built.

A programmable one-dimensional linear harmonic oscillator, built to facilitate a research project I was doing.

A jig for the characterization of elastic and hyperelastic materials through biaxial stretching, built to facilitate a research project I was doing.