I made this based off of Big-E's original design. Prints in minutes and your MicroSD card should slip right in there. It was a pain trying to plug in the card by hand--I'd have to pull it out with some pliers and I was always afraid of breaking something. Now it's quick and painless.
2/26/16: Glad to see my very first design on Thingiverse is still getting used to this day! One precaution that I will mention, based on my experience, is that while this works great to insert and remove SD card, it also makes it very easy to bend and break your SD card while it's in the slot. Be careful! If you have any feedback in that regard, please leave a comment! Happy printing.
Print on its side so it's easier to snap off. I made mine at 70% infill, although the part is so small I'm not sure how much of a difference it makes.