Please print one tray and one body part first and have a look at how they fit each other. Also read the original design for answers to most of your questions.
Kudos and special thanks to Ivan, the original designer. I love the design.
The author remixed this model.
I wanted a different number of Raspberry Pi's in the rack, so I resized several core elements.
All rack bodies are the same length (unlike the original) so you make and mix.
For example, for the rack bodies you can fit 15 XS and 2 Large (SSD) versions, or 18 XS versions, or 12 Small and 2 Large (SSD) versions, or 12 Large (SSD) versions, in a single rack.
In addition, I combined the different rack tray functions into one and made it compatible with Raspberry Pi 5 (there are a few electronic parts on the Raspberry Pi 5 which interfere with the current tray design). You can now use the same rack tray to attach an external SSD, or attach internal SSD, or none at all.
Also I resized the width of the rack tray so the print fits better in the rack body (without relying on horizontal expansion -0.1mm, better for PrusaSlicer as this does not support it). Depending if you print with supports, some very minor sanding may still be needed.
I still recommend using the following settings (from the original design):