Because there are many moving parts I recommend making the test print first. Test fit the pieces and choose parts that are smooth without being excessively loose.
Put an M3 screw through the holes on the link arm. The printed part should swing freely without friction. If the hole is too tight you can drill out the hole. (If you do not have a 3 or 3.1 mm drill bit, a 1/8 inch drill bit is 3.18 mm.) An M3 screw should thread into the hole of the sliding arm without being loose.
At the start of this project I made the decision to use screws for axles. This makes the joints smooth and robust, but introduces required hardware.
Some lubrication is recommended (but not required) where the gears contact the gear housing.
Follow along the pictures for a detailed step-by-step assembly guide. I labeled the location and size for screws, as well as areas that need glue and lubrication.
When installing screws for the arms, be sure to use sufficient downward pressure while rotating to get the threads started. Protip: Insert a slide arm into the faceplate first and then try installing a screw.
Thanks for visiting, and enjoy!
The author marked this model as their own original creation.