A simple factory organizer with optional magnetic attachments. The center ring is designed to print on a 200x200 or larger bed.

The Connector pin can be used to connect the factories to the middle ring instead of magnets.

I recommend printing a single pin with 50% infill. This is to avoid the extra burrs that occur when printing multiple objects. I recommend gluing one end into the factory ring. From there is just pushed into the center ring when playing.

Magnets (optional)

Hole for magnets is very tight. No glue required, though you may want a drop if you have small children or animals. Be sure to get the polarization the same for each factory and then the opposite for the ring. It is near impossible to pry the magnets out after you squeeze them in.

I used 6 x 3 mm magnets available through Amazon. https://www.amazon.com/gp/product/B077K364Z7

They are actually only 2.65mm thick.