SD_Card_Six_plus_Three

This is a modified version of the [card holder from @PhantomEbay](http://www.thingiverse.com/thing:883556) Which looked like a good starting point. Newbie box-checking problem fixed, so properly indicating 'remix' now. :)

I cleaned up a bunch of extra faces, and rounded off a bunch of edges. Also added a chamfered key-ring hole, and did a test print as shown. The lower layer under the reg SD cards was a bit thin, so added a bit to that too.

Also wanted to remove the sensitivity to slot-width for a friction fit, so added some tension-bumps to each bay to give a slight bit of extra friction. Should help for print-to-print variability.

Will tweak again if I come up with any other brainwaves, but feels pretty good now.

UPDATE
----------
Use the xxxx_D.stl file if you have downloaded an earlier one. Found that the tension bumps were a bit too tense in the altered version after a second test print.
If you printed the earlier xxxx_C version, just sand the bumps down a litt