The miniature version of the Rack and Pinion Display.
Attach the "holder top - lower part" to the "holder bottom", then fit the rack before attaching the “holder top - upper part". Then insert the pinion and pinion cap, and attach the knob.
If the short pins fit too loosely into the corresponding holes, you can use a hard object to make a slight divot in either the hole of pin so that it fits more snugly.
The author marked this model as their own original creation.