Lego. Is there anyone who doesn't love letting the creative juices flow to build everything from 3D printers to cars you can ride in to musical instruments? During the recent MidiHack weekend in Stockholm, Sweden, an unofficial collaboration between a university professor and three developers from Native Instruments yielded a rather impressive step sequencer, complete with XY pad, faders and rotary controls.

Bauhaus-University's Kristian Gohlke and Tobias Baumbach, Bram de Jong and Tobias Baumbach from Native Instruments made up the MidiHack Lego Techno team. Gohlke told us that many of the bricks used were leftovers from a project he undertook for Legoland Germany in 2006, and were not modified in any way to make the step sequencer.

"All Lego bricks are unmodified to not interfere with the playing experience and keep things real (we put this as a constraint upon ourselves)," he said. "The only somewhat exotic part is a very rare transparent baseplate for the interactive surface of the table. A standard webcam is mounted underneath the baseplate. The image is processed by a Python Script using the OpenCV Library to track the bricks."

The upper surface measures 54 x 54 Lego brick studs, and the structure rises some 50 cm (20 in) from the ground or desk on which it sits. Lego pieces on top of the transparent plate are used for controls like a filter on an XY pad, a fader for beat delay and a rotary dial for reverb.

The assistant professor in the Product Design department at Bauhaus explained that information like brick color, position and orientation obtained from the camera image gets converted into OpenSoundControl messages. These are then bumped over to a second computer running a sequencer that sends MIDI into NI's Maschine groovebox to output the sounds.

"The tricky bit was to not track the users hand but we succeeded at that as well," Gohlke told us. "Of course we could have used other sound generators as well, as the whole thing simply spits out MIDI, but hey, Maschine is kinda cool. In Maschine we can control effect parameters, using rotary and sliding controls made from Lego."

The build slot for the Lego Techno was 24 hours, but Gohlke confessed that, "we even managed to get beers at night so all in all it took a little less than 24 hours to make. Being real Master Builders, of course, we used no Kragle for the construction."

Work on expanding the project's capabilities continues. Meanwhile, have a look at the short demo from the first Stockholm MidiHack event held last week.

View gallery - 7 images