Here’s a little synth I built a while ago using the Arduino Mozzi synth framework. It’s unfinished but capable of producing some bleeps and bloops. It’s main features are it’s body is cut from a single piece of wood and it uses capacitive touch inlays to trigger the sounds.
The notes are notionally tuned to the pentatonic scale, but the chaotic nature of the firmware as it currently stands make that a little moot.
The body of the synth is made from a solid piece of wood, this presented the main challenge with it’s construction as my CNC machine couldn’t cut to the required depth. To get round this I 3D printed a number of templates to cut out the wood using a standard hand-held router.
The leftmost jig was used to cut the outline of the synth. It also has removable plastic squares where the inlay pockets are cut from. Making them removable allows the cutting of alternating pockets without the router distorting the shape of the jig.
The next jig along is used for holding the synth to the bed of the CNC machine so the finer details, such as speaker grill and control knob holes, can be cut from the body.
In the center is a failed attempt at cutting the inlay pockets. At some point the router or jig slipped and distorted the line of holes.
The 2nd from right is the jig used to cut the recess in the rear of the synth. Once the main outline has been cut the synth can fit into the jig and a lip guides the pocketing of the inside of the synth.
Finally the rightmost is an initial experiment to test the suitability of the jigs and see if the inlay technique would work successfully.
Unfortunately I didn’t capture any photos of the inlay process, but it involved grinding up some aluminum foil an old blender until it was a relatively fine powder. A hole was drilled through the bottom of the inlay pocket to the inside of the synth and a wire glued in place. Then finally the inlay pocket was filled with aluminum powder then super glue was used to fix it into place and the top was sanded flat.
The above photo shows roughly how the jig which held the synth to the bed of the CNC machine worked. Note that the screw holes in the wooden blank to hold the top jig in place are positioned such that cutting the fine details will obliterate them.
The electronics are fairly simple. An Arduino Nano clone is the heart of the operation. An AT42QT1070 breakout board is used for the capacitive touch sensing, and a small 0.5W LM386 amp board is used to make the noise. A 3D printed ledge around the inside of the case has nuts heat-set into it to allow a back cover to be screwed into place.