Successfully assembled and tested my first map for Doom over a couple of nights. It isn't pretty, nor would I claim it to be especially good in other ways, but it exists and that is its own kind of triumph.
It's got a lift (so many texturing mistakes before I got it okay), a door (had to set aside the map after about an hour of failing to get that right and re-check a tutorial), monsters, a key, and a remote-activated key door. Ended up being surprisingly difficult but consistently beatable for me with keyboard + touchpad, which is also a small lesson in how to balance encounters.
Am quite satisfied. Will probably make a go at building a more serious practice map in a day or so and see how that goes.