I needed a little holder to fit in the bottom of the plastic case that came with the mini speaker I got at Kmart around Christmastime a few years ago. TM2114L3's 4-slot holder remix http://www.thingiverse.com/thing:1323070 was just right, except that when I scaled up as instructed, I found that the SD cards tended to slip down in and I had to turn it upside down to dump them out. This version has been re-scaled and rotated to print in the right orientation and the height has been reduced so that the cards stick out just enough to grab them using the little groove.
Unless your printer prints perfectly without any blobs or strings, you will likely need to take a small file and clean out the slots to achieve a perfect fit for your micro SD cards, but once filed out the slots should fit cards nicely.
miniSDholder_shorter.stl | 54.9KB |