The bonnet I made, is the rainbow one: the other is the one I used for inspiration and a guide. I don't know what the sizing is on these: all I know is that they JUST BARELY fit my 3 1/2 year old, who wasn't extremely happy to have them on her head. So maybe they'll fit as little as a 1-year-old? I really haven't the foggiest.
I started with a circle. Well, half a circle. Anyway, the thing has a diameter of about 12", except for a little bit on one edge, where I wanted to make the hem at the back of the neck. I think that it's not necessary, to add the bit that juts out from the circle, but I added it anyway. The bit that juts out, is about 1/2" to 3/4" deep. I cut out ONE of this pattern piece, after folding the fabric in half where you see the arrows saying Cut on Fold.
Next, I made the brim. Or maybe I started with the brim and then did the hat part. But that's not important. The brim is easy. You'll have sort of a long half oval when you cut this out. I cut two pieces of fabric (again, folded in half where it's noted), and two of interfacing. I think if you used thick interfacing you could use just one layer, but I had fairly lightweight stuff.
Next, I added interfacing to the backside of each of the fabric pieces, for the brim, and sewed them together (fronts of fabric facing each other) except for a little gap that I used for turning it right side out. I used a 1/4" seam allowance. And then, of course, I turned it right side out and topstitched the whole thing. Oh and I clipped the corners and made little notches along the curves, before I turned it right side out.
After that, I created the back hem of the bonnet. I used the part of the back that juts out from the circle, and turned it on itself twice so I had a nice clean hem with no raw edges, and sewed. I had to go slowly, because well, it's rounded, and it's hard to hem rounded things! The whole thing looked more like Just A Circle, when I was done.
Then, the part I was dreading: gathering the part of the bonnet that attaches to the brim, and attaching it. I set my sewing machine to it's longest straight-stitch setting, and sewed around the raw edge of my circle piece, leaving longish thread tails on both ends. I sewed this line about 1/4" in from the edge of the fabric. (No backstitching!!) I pinned some places on both the bill AND the circle, so I would know I was gathering correctly. This is just like making a ruffle (a total pain in the rear, I say, but quick work because it's a small item, so I got over it). I pinned the middle, and then in quarters, so that there were three evenly spaced pins on the brim and the circle. Then I pulled one string on one end, til the circle was gathered to the right length on one side, and repeated it on the other side, distributing the gathers as needed, so it looked even and not patchy and weird. I did it sort of like this, but didn't think of doing more than one row of stitching... might have to try that next time!
Lay the ruffled edge on the straight edge of the brim, and PIN, PIN, PIN. Make sure when you turn it right side out, that the whole shebang looks right. Turn it right side out to make sure, before you sew. I had to unpin and redo, and can only imagine how mad I would have been if I had SEWN it wrong and had to do that whole step again. Now sew it together. I actually sewed two lines- one about 3/8" in, and one a little closer to the edge.
Add your ties. I made mine with the fabric I was using for the rest of the bonnet, but you could use wide ribbons too, if you wanted. I cut 3" wide strips of fabric and turned each edge to the middle, then folded them in half, so I ended up with ties that were 3/4" wide or so. (I can't remember how long they were, but probably 18" long or so- you can make them however long you like). These I sewed on to the inside of the bonnet where the brim and the neck hem met. I did a couple of lines of stitching to make sure it was secure.
Last: elastic. I used 3/8" wide braided elastic. It goes all the way across the neck opening, on the inside of the bonnet of course, right above the hem. I held it where it needed to go, and stretched it hard, while I did a straight-stitch along one edge of the elastic. Then I did the same thing on the other edge of the elastic. That makes it pretty, but you could probably also do a 3-step-zigzag stitch all the way down the elastic too, instead, if you wanted.
I don't mind if you make a million of these and sell them, by the way.