So what to do with a dozen cards when on a 7 night cruise and OCD enough to want to pack as lightly and compactly as possible? I could not find a high capacity compact case for just SD, they always seemed to have extra sleeves/slots for sizes I don't use, and were bulkier than I cared for.
I can sew, and have made some foam/fabric ones before, but they were only bandages, not a cure for my ills. Lo and behold at the local Big Box store today, in the travel toiletries section, were these little beauties - toothbrush head covers. It was the little angled notch that intrigued me, so for a $0.97 gamble, I grabbed a pair and headed for home with fingers crossed.
It is difficult to see, but inside are very shallow ribs - I trimmed them out with a simple wood chisel to smooth the inside completely. I also used a rotary tool to relieve the ridge on the lid by the hinge so I could be sure it would clear the cards as well. In retrospect, it wasn't necessary as the lid clears perfectly.
The cards are held with just enough tension to not just fall out, but a light shake drops them into your hand as easy as a vitamin from a bottle.
I'm going back and get some more, of a different color, so the unused go in the yellow, and the used go into the red. I'm now organized and worry free which cards are which, how many I have left, etc.
The final caveat is these are NOT watertight by any means. There are three tiny vent holes in the bottom, and the large hole in the lid (where the toothbrush handle would go through). While the vent holes are easily sealed, the lid is simple not sturdy enough to trust, even if you could find a way to adequately seal the hole in it.
I'm still looking for a waterproof/water resistant solution, so please share if you have an idea. Thanks for checking out my first contribution!