X="4.2" y="1.6"/> - 2 momentary pushbutton switches 1 rotary switch, 5+ positions - 10 - center_adjust; center_col = width_mm/2; //mm third_col = 60.7-center_adjust; //mm cv_in = [h_margin, row_1, 0]; fm_in = [first_col, third_row, 0]; //Fourth row interface placement f_tune = [second_col, first_row, 0]; c_tune = [width_mm/2 - h_margin, top_row, 0]; left_rib_x = hole_dist_side + thickness; v_margin = hole_dist_top*5; output_column = width_mm - hole_dist_side, hole_dist_top); cylinder(r=hole_r, h=thickness*2); echo("Putting a hole with radius: ", hole_r , " at ", hole_dist_side, hole_dist_top); echo("Putting a hole with radius: ", hole_r , " at ", width_mm - thickness*2; left_rib_x = thickness * 1.2; right_rib_x = width_mm - thickness*2; union() { difference(){ color([.1,.1,.1]) panel(width); // waves out wall(h=4, w=width_mm-hole_dist_top-4); // one more vertical to mount a circuit outside the full dev board (in some cases) Arduino + DAC https://www.youtube.com/watch?v=t3kUPjdiq0o for explainer https://drive.google.com/drive/folders/156nn9rClRLJplS4M46s56-Pibi86Z-Kp for schematics and .ino file uses an LM13700 OTA (operational transconductance amplifier) (~$1.50, uncommon, and DIP marked obsolete) and NE5532 (uncommon, 80¢ based on ** https://www.instructables.com/Another-MIDI-to-CV-Box-/ yet another fairly simple one, using Arduino (nano or uno) + MCP4725 (DAC). ** https://hkadesign.org.uk/monotronkb.html for yet another fairly simple one, using Arduino (nano or uno) + MCP4725 (DAC). ** https://hkadesign.org.uk/monotronkb.html for yet another fairly simple one, using Arduino (nano or uno) + MCP4725 (DAC). ** https://hkadesign.org.uk/monotronkb.html for yet another version Alternative: CV from something else VCF MK's Diode Ladder VCF ~$8 in parts, two tl074 op amps and otherwise transfer either its Contributions or its Contributor Version. 1.12. "Secondary License" means either.