So I went online today and looked at websites offering the most gorgeous darning eggs made of beautiful hardwoods, buffed to lovely high gloss sheens. I drooled a little, oh yes.
But instead of ordering one, I went to Hobby Lobby and bought these:
With some judicious two-part epoxying, this is what resulted, my version of a darning egg:
It ain't pretty, but I think it will work.
I've never had any proper training in how to darn a sock, so I don't know the correct technique, but this method of creating a basket-weave "fill" in the hole area, anchoring it into the good stitches of the surrounding heel, has seemed to work adequately in the past.