Credit to jcarolinares for the idea I've gone ahead and remixed the Question Block and cartridge holder into one print.
Switch cartridge and micro SD holder
Super Mario Question Block:
Printing and assembly video https://youtu.be/p1veEHFmAoI
You'll need to print:
1 x box
1 x lid
4 x question marks
16 x screws (4.5mm)
As this is a remix I didn't make changes to all of files only the main box. If you're having trouble fitting the question marks in place, try sanding or slicing back the bottom edge 1mm or you could use a thicker adhesive such as a hot glue gun. If anyone edits the files themselves feel free to send them to me and I'll update it.