One of the first things I sewed, without a pattern, was a lampshade...more like a fabric cover for a wire tapered barrel shaped lampshade. I measured around it...but didn't realize the shape I'd be cutting was not a rectangle and didn't buy enough fabric.
Another project was a needle roll for my double point needles. I knit a long strip on my KnitSmart knitting machine and felted it. Then I sewed fabric to make the inside. I really didn't know how to order it, how to plan it, etc, and most of it ended up being top stitched. I thought I was clever because I sewed on a flap to cover the tip end so they couldn't slide out.
As I've progressed, I've had a few of these projects. The Internet, especially Pinterest, have helped as there is now a pattern for almost everything. Almost.
My husband bought me a new phone. My old one was so old I couldn't run any apps anymore, or even take selfies. It's a great new phone...but since it's a refurbished phone and not the latest and greatest, the case selection was lame. The salesman said to buy from Amazon and after checking a few places, I finally did find some cases on Amazon--though two I picked out wouldn't mail to Canada! In the meantime though, I needed something to protect it in my knitting bag, coat pocket, etc. "Gorilla Glass" is tough, but I'm not sure about knitting needles!
I knew what I wanted. A zippered bag, with a wrist strap, and a clear plastic screen area. When sizing, I made sure to make the zipper at least the size of the phone, remembering that some of the zipper length is lost once sewn in. I did the little tabs over the zipper. I wanted it lined with PUL. I thought I had it all figured out, top stitching around the plastic window, thinking I was nearly done. Then, I realized something. I actually don't remember what that was now! But for some reason, I could not finish it with the PUL on the front piece! I think I wouldn't be able to turn the bag right side out after sewing it together. So I changed it so the PUL was only on the back piece.
I added two male halves of the snap so it could be a large loop or I could make it snug around my wrist. The ribbon wasn't double sided so I did sew it together to make it reversible. And yes, I did trim those threads. I was just so excited to share a photo on Instagram LOL.