Updated to add v3 (Dec 18, 2021):

• Rebuilt from scratch
• Parametric design, number of laptops/iPads and the space for each is now handled with parameters.
• Uses less filament (less cost to print) than previous iterations
• Less surface area on the build plate has eliminated warping on my PETG prints
• Supports recommended, but brim is no longer necessary and cooling is ok.

Updated to add v2:

• The divider arms have been updated substantially:
  • made uniform
  • reduced in height
  • fillet has been reduced to be more consistent with the idevices this is holding
• A chamfer has been added to the device slots
• The height of the base plate has been increased slightly
• If printing PETG, suggest the following settings:
  • Infill 30%
  • add a brim
  • turn off cooling

I had challenges with the base warping right at the divider arms, which I believe has to do with the higher layers cooling and pulling at the base. Adding a brim and turning off cooling (and redesigning the model a few times) eliminated most of this. Winter weather and the printer being right next to a window was probably not helping here.