This was an old sweater of mine whose zipper stopped working. The other shirt I used was an old light brown shirt of my husband's. I ran into this tutorial on Made and was inspired.
My version of the sweater vest ended up slightly different than hers. Mine had to open up through the front because I was using a old cardigan instead of an old sweater. Once I removed the non-working zipper, there wasn't enough sweater fabric left to do anything with except have a vest that opened.
I opted for buttons instead of a zipper because I had some that matched, and the only separating zippers I had that were approximately the right length were in red and white, both of which I thought wouldn't look good. I debated whether or not to use the hood from the cardigan, thinking that we get a lot of use out of hooded vests. But they also aren't as polished/ fancy; in the end, I let me son decide, and he said "no hood."
I also did the binding slightly differently than she did in the tutorial. I didn't have any ribbed fabric, so I took the bottom band off of a man's size large shirt for the middle section and it fit perfectly. The arm bands were the bottoms of the sleeves from the same shirt, which I didn't even have to open up. I attached them all the same way that Katrina attaches the legs and waist of her soakers, then topstitched to make the seam lay flat and make it look more polished.
With the cardigan arms, I made pants. I cut them off and angled a crotch into the fabric (you could easily do this by laying a known pair of pants on top or a pattern you like). Then I added a waistband like my favorite pants do, using fabric from the man's shirt to hold the elastic.
These are a bit long, but really trim and cute when worn. The contrasting color stitching that was left in the center adds a nice detail, and actually looks like a zipper at first glance.
With the rest of the man's shirt, I made two pairs of pants.
This pair was made from the arms in the same manner as above. They are a bit wide when worn, and I may need to take the sides in. The length is good, though. You can see on the hem where I removed the arm ribbing for the vest.
These last two photos are of the second pair. These were made from the body of the shirt and using my favorite pants pattern. I am adding length to this pattern lately, though, as my son has gotten taller but not wider. Whenever I use it, I add about 4" to the bottom.
When I cut them, the backs ended up with some stitching left from the original bottom of the shirt where I removed the ribbing for the vest. The front didn't. In order to keep them the same length, I hemmed them by sewing a zig-zag over the edge of the front side. These ended up a bit long, so I may just hem them for now and take them out as my son gets taller.
I like the detailing that remained from the original shirt on this pair. On one side of the back, you can see the sewn-in "V" from the center middle of the original shirt. On the front, you can see some of the original stitching that attached the middle of the shirt to the arms.