This is a cool chain based storage system that I came up with for gel pens. it looks good on your desk and allows you to easily scroll through your colors. it features a planetary gearbox and chain drive system.  

Assembly instructions

Step 1: Chain assembly

Assemble 36 pen holder links into a chain using filament as the pins. make the pins ~.5in(13mm) long. you may need to crimp the pins in the middle with pliers to help keep them in place. Assemble 36 pen holder links into a chain using filament as the pins. Do not connect the ends of the chain yet.

Step 2: Shaft Assembly

Use CA glue (superglue) to attach the Planet Carrier to the Shaft. Be carful not to get glue in the hole of the shaft.  

Step 3: Sprocket installation

• stack the 2 sprockets on top of each other so that both the teeth and the middle hole are aligned, make an alignment mark across one set of teeth
• place the sprockets into the base and line up the mark with the same edge on the base
• slide the shaft in through the top connecting both sprockets
  !! make sure sprockets are aligned with each other using the mark you made. be carful not to flip over one of the sprockets after making mark or they will not align.

Step 4: Chain Installation

• Wrap chain around base ensuring proper sprocket engagement.
• Install last 2 pins to connect chain ends.
• Make sure indented portion of chain links is upwards(this is for the clips on the pen lids)
• You may need to push the lower sprocket up from the bottom to get it aligned with chain
• Rotate shaft manually for a few full rotations of the chain to ensure nothing is jamming and to pins come loose

Step 5: install covers

• Slide on the bottom ring followed by the top cap.
• You can glue these if preferred but id will make it impossible to service the chain in the future so I don't recommend it.
• Rotate the chain several times again to make sure nothing binds up.

Step 6: Gearbox Assembly

• Add knob to crank.
• Place 3 planet gears on planet carrier.
• Drop crank into gearbox.
• Test.