Well, in truth, it's not the pocket itself that is serendipitous. In fact, this pocket is not going to be particularly useful for anything now that I'm done making it.
But it happens that the goals I listed in my last post included mention of welt pockets as a technique that has left me confounded. And then, ta-da, Carolyn of Handmade by Carolyn posted a very clear and detailed tutorial on double-welt pockets. What made her explanation work for me where others have failed is not only her detailed step-by-step approach with photos but also her description of where you have to be precise and just how precise you have to be.
Mine is not perfect—the sides are just a bit off vertical, and the upper and lower welts overlap a little at the ends—but it pleases me no end. I do need to figure out how to make a skinnier button loop without having my machine eat it as I sew. (I have a couple of ideas on that: get a throat plate with a smaller hole, and start with a wider bias strip so that the feed dogs on at least one side have something to grab onto.)
So now I have a pocket on a patch.
An entertainment note:
Along the lines of my earlier plug for GeoGuessr, which I still think is one of the best online games ever, take a look at Kern Type. The instructions read, "Your mission is simple: achieve pleasant and readable text by distributing the space between letters." Tell me I'm not the only one who finds this addictive, please!