Would it be possible to fit a micro SD card reader on the side of the 13’s chassis? Just like the left side has a 3.5mm jack, is there enough space to drill a hole and solder a reader - has anyone asked about or tried that?
Where do you plan to connect it to? There are no internal usb ports. Why not use microsd card adapter?
No free available internal ports, but you could steal one from the web camera or the fingerprint reader, if one doesn’t use or want one of those. Alternatively, you grab usb from one of those, but split it with an usb hub chip so you lose no functionality. I’m sure a small board for the hub can be stuffed somewhere. This is provided you don’t mind your microSD reader only having usb 2.0 speeds available.