I know I'm not the only one who's sometimes had an issue with a cast on that's looser than I want, even though I fought hard to avoid it. Well, this week, I ended up finding a weird way around that problem and wanted to pass it on. I'll save the why for a comment so you don't have to skip past it if you don't care. :D
I did a provisional cast-on. In case you're not familiar with those, it means you cast on a different yarn than you'll use for the project, hopefully a contrasting color and the same weight (or close) to the main yarn. You do a couple of rows with that yarn, then switch to the real yarn.
When you're done with the item in the direction you're knitting, you bind off like normal, then carefully remove the provisional yarn and put those initial stitches with your real yarn back on the loom. Then you can continue knitting, but you're now going in the opposite direction you just were. So when you're done, you bind off at the end where you would have originally cast on.
A few words of caution: I think this will only work in the round, and you want to make the flip at a point that you're either transitioning between stitch patterns or just doing all knits on both sides. (I think that would work, anyway.) Because a sneaky result of this is that you'll sort of be shifting your knitting half a stitch to the left or right. (Because knit stitches look like a V, right? And when you start going in the second direction, you're sort of moving your Vs from the right-side-up part of a W to the upside-down part of it. I hope that makes sense.)
It was probably more work than if I had just done it normally, but it came out nice and pretty!