You need to print the following amount of parts:

• 4 under
• 4 top
• 6 (3+3) full, I.e. 3 in each color. 

This model is almost a first layer test. Depending on your infill type. 

I printed mine with the following settings:

• No bottom or top layer! 
• Hexagon infill pattern with 7.5 % density
• No skirt or brim.
• 10% speed for the first layer
• And only 3 parts at a time

You can of course choose any infill pattern you like, but make sure to have no bottom or top layer if you want to be able to see the pattern.

It is possible to fit 4 pieces onto the print bed, but your first layer have to be pretty good.

I managed to be able to print 3 of the “full” part at once and only 2 of the “under” or “top” model. 

Make sure your z calibrations isn't to low so the first layer is too squished together. Otherwise you won't be able to assemble the pieces together.

The assembly is as follows: 

1. Take all the “full” parts and flip the ones you print in the top color so their slits are pointing down and slide them into the “full” parts version of the color you printed the “under” in. The “full” goes into the center slot and the two outer must slots. 
2. Take all the “under” parts and slides them into their slots. There is no order.
3. Repeat for the “top” parts.

If you're print isn't perfect, which is completely fine, the assembly should still be manageable.