Testudor Adjustable Spool Holder - tightly stackable - for MMU

I needed a set of spool holders for a tight space, even less than is available on Ikea Lack table. I also wanted a spool holder that's easy to operate, screwable to the desk and won't waste even a mm of space.

So how it works?
You can align the spool holders from top left corner to the bottom right - version A
or from top right to bottom left - version B, spacing is in the photo. 
That way racks will fit in the hole of the neighboring spool holder wall and spool holders will have full range of adjustment. 
 

Spacing:
Minimum space needed between the spool holders (fully closed) is 30mm, each rack will extend to 45mm. With that configuration 5 spool holders will need only 52cm of space and will allow 70mm spool in each spool holder (prusa and most other 1kg spools)
For Ikea Lack table that is 55cm the right spacing is 45mm for edges and 37.5mm between the spool holders.

Edit:
Added numbered topplates for mmu printing (vertical and horizontal) in 3mf format
Added guide spacers + alignment tools.

Other parts:
9x 608 bearings
4x M3x10 or smaller screws for roller blockers (self tapping)
4x M3x16 screw and nuts for body
2x M4 wood screw for fixing in place
 

Print and assembly:
Don't mix the A bottom and sidewalls with B variants, the two variants are for different direction of stacking.
Use 4x M3x16 screws for main body instead of M5 
Use PLA for well tuned printers, PETG has a 0,3-0,8% of shrinkage that can make the parts not fit as intended, roller blockers are one way to mitigate it.
Print racks with 3 wall thickness.
I've added alignment guides.3mf with different spacing options. Print 4 of the desired spacing and place them under the racks with the spool holders fully closed.

• different gear locking mechanism
• shortened racks from 120mm to 106mm reducing max spool size from 18cm to 16.5cm
• changed 4 body screws from M5x16 to M3x16
• Changed side holes to allow neighboring spool holder rack to pass trough
• Added M3x8 or M3x10 spool bearing screws, and roller blockers (optional).
• Added feet to the walls for more stability.
• Needs only 30mm between the spool holders - if aligned in a way that rack pass through the neighboring side wall holes.
• Added numbered top plates 1 to 5 for MMU multi color or layer coloring.