I've gotten a lot of mileage out of the dress I made for my niece (and so has she), but it really was high time to make something for her twin brother.
It's 4ply mercerised cotton from the dollar shop. (! cost more than a dollar, but a good price. And they had a colour that I liked for him - it's hard to find 4ply cotton in interesting colours.) A lot of knitters hate using this kind of cotton, and it is considered to be more for crochet, I think. I wasn't sure at first, and I'm not a fan of really shiny, hard cottons, but this one was fairly soft and it swatched into a really nice fine drapey fabric. So I went for it. I added some thin stripes with leftover Tofutsies. I liked the way this added a few other colours without making it like I threw a rainbow at it. It's hard to get much of a range of colourful clothes for boys. I think this will brighten up lots of his outfits.
I started at the bottom, casting on enough stitches to get the right width/circumference. I made it a little wider than the roomy t-shirt we measured, to give a little growing room. And I used some ribbing up both sides to draw in any extra fabric a little bit so it would have that room but not look too baggy. I also did some lines of purl stitches, for some fun texture and to make it a bit less serious - it is a toddler garment after all.
The rolled edge was a few rows of stocking stitch before establishing the ribbing. I usually like this effect a lot. It doesn't sit quite right in this cotton, but I thought it was ok. I knitted the body in the round. While this was in progress I looked at a number of vest pictures and patterns to work out the basic proportions for when the armholes should start (about 2/3 of the way up the body I think).
From that point I adapted this pattern for the v-neck and armhole shaping. Then I seamed the shoulders and picked up stitches for the neck ribbing. And then, I panicked about the apparent smallness of the neck hole. I really wanted it to be a standard v-neck vest and not a baby vest with buttons on one shoulder. But I was quite worried it wouldn't go over his head without tears! So I had to spoil the surprise and get him to try it on.
It was fine! Well, apart from him, with his 2-year old fashion sense, NOT LIKING IT. Apparently he's getting over that now. They say you may have to present new food options many times to a toddler before he will try them. This vest might be a bit like that.
So I took it home and finished the arm holes with ribbing, and wove in sixteen thousand ends. Approximately. I normally don't mind weaving in ends, even when there are a lot of them. But it's just not fun in cotton; they are so much harder to hide. I did get it done though, and I was very happy with it in the end, as it fit the kid and matched my initial vision pretty well.