\Update: I originally described this as the place where I would document the post-painting look, but that's really only related to the tile job by physical distance and by being a pre-requisite to putting on the last trim pieces of tile. Here are some photos of that trim area with the new paint nearby. The red showing through is the RedGard membrane.

One of the reasons I procrastinated on this for so long is because of the trickiness of cutting the trim pieces for the irregular outline of the tub itself. Close-ups of those areas:

I already had one of those tools with the little plastic sliders that can capture and reproduce a curve (aka, a contour gauge), but it's only about 6 inches long. I'd have to do it in segments to get all 15 or so inches. Luckily, I happened across an inexpensive contour gauge that was a pair of 5 inch and 10 inch gauges that can be joined together. There are several similar contour gauges like this available, but this one happened to be on sale for pretty cheap when I was shopping. It's not perfect for this scenario because the shape of the ends would not let me get all the way to the floor, but it was pretty good. I could approximate the bottom inch or so as an extension of a straight line.

With that contour gauge, I was able to capture the two irregular areas. I transferred the curves onto those drywall shim strips (yay, yet another use for them ... only about 85 out of 100 left) and from there onto the backs of a couple of my trim pieces.

I cut out those shapes with my wet tile saw and finished up the rounded corner sections with my grinder. It took a couple iterations (and trips from upstairs to the basement) to get a good fit. I was conservative in how much I cut away each time since it would be impossible to put it back. (As it was, I had to start over with the right end piece because it fell over and the thin part snapped off while I was fitting the left end. You turn your back for one second, and ....)

Here's one end with the trim pieces in place but not yet caulked.

Those trim pieces are not in a wet area and are not in a change of plane, so I could have used grout between and around them. I have both grout and caulk that are color-matched. I decided to use caulk since it's a bit eaier to work with. Here's a little bit of the finished caulking:

As the final Final FINAL piece of this tile job, I did the same sort of caulking where the tiles meet the ceiling. Here's a glimpse of that: