So I searched around on Etsy and Amazon, and of course I found things that would work okay, but weren't exactly what I wanted and/or weren't in my price range. So of course, I was like, "I'll just make one!" But like, all of the sudden. With almost no plan. Because that is how I roll.
I followed this tutorial (VERY helpful for figuring out the intricacies of layering for the double zippers). And of course, as I sat in my craft room and thought, "Hmm...what kind of color scheme or design should I pick?" the only thing my brain came up with was "SHERLOCK."
I used my leftover skirt fabric, some maroon for the lining, and yellow zippers and ribbon (because of the smiley face). It's perfect and I love it. Big enough to hold everything but not unwieldy. It can clip onto my belt loop (preferred), or onto the adjustable strap I made for it (plan B for my belt-loop-less low rise maternity pants [no I'm not pregnant -- low rise maternity pants are comfy and stylish]).
And although I wasn't actually trying, because trying seemed like a giant hassle that probably wouldn't work right anyway, the pattern actually does match pretty nicely on the front! Woot!