A simple remix of a really good idea from Dranoweb. Hmm, actually it is taking a good idea and making it more complicated, mostly.
Print 2 of the case and 2 of the plug parts, connect with 2 x 3.5mm (No.6) screws
the micro SD 'tool trays' are 2mm thick the others are 3mm, so depending on how many and which trays you are printing you might need to adjust the height of the plug.
As supplied the plug stem is 20mm tall, this is sufficient for 17mm of tool trays, i.e. 3x3mm & 4x2mm. If you are printing a different combination then you might need to add or reduce the plug height accordingly. Basically calculate the height of all of your trays then add 3mm.
I like to keep a note with the spare micro SD cards to remind me of which Raspberry Pi project this image belongs to, hence the single micro SD holder, with space for a piece of note paper.
Note that the plug has a recess cut out to fit a coin (10p, that's approx 2mm x 24.5mm ⌀), you might want to print this part with support
I used a 0.6mm shell. Found that 0.15mm or less is better to print the thinnest part of each tray at 0.5mm.
I printed these parts in PLA on 2 different makes of machine (QIDI X-One2 & Ultimaker 2) and they fit together well enough.