So I took JasonD's Battery holder, and mixed it up with iomaa's USB-SD-MIcroSD holder, and i came up with my own, JasonD's compatible version.
Needs some tweaking, but I'm still working on it. Let me know how it works for you.
JasonD's work here: https://www.thingiverse.com/thing:954557
iomaa's work here: https://www.thingiverse.com/thing:2835728
9 slots | Each slot holds 1 UBS stick, or 1 SD card, or 3 (or 2) SD Micro cards | Holds a maximum 9 UBS sticks, or 9 SD cards, or 22 SD Micro cards, or an undefined combination of those three.
Props to JasonD and iomaa. This wouldn't exist without their designs.
EDIT: I decided to remove 1slot group, as flashdrives were too close together.
I also increased the size of the USB and SD slots, as they were too tight.