Bolt latch with rack and pinion with 9g servo or step motor

thingiverse

I've designed this rack and pinion latch to build some chest/box door latches that work with Arduino, which is great fun for kids. To mount the parts over thick double corrugated cardboard, you'll need a base. The cardboard will be sandwiched between the base and the parts. Since it's 3D printed, fitting tolerance may not be perfect with your printer, so you might have to adjust some diameters or clearances after a test print. Have fun building it and post what you've done with it. Update 2020-05-23: Support and spurgear added for step motor. My 9g servo was a total failure (I don't know the brand, but the unit in the picture came from an Arduino Elegoo starter kit), so I modified my design to use a step motor that I had on hand (from the same kit). I changed the support and spurgear to accommodate the step motor. I also added a small push button holder at the left end of the support so you can zero the step motor easily.