Throw pillows out of old t-shirts.

My family has one. I'm not sure we'd get one if we didn't already have it. With that said, I've repaired clothing, backpacks, and a fairly expensive musical instrument case. For the latter repairs, I broke a few needles, and had to work the mechanism by hand, a stitch at a time, because the motor wasn't strong enough, but it got the job done.

As for making things, curtains. They're not hard because they're rectangular, and mainly just need cutting and hemming, but the result is sizes and materials that would require buying something custom made.

Camping gear, hammocks, bags, any small change or repair. Strap breaks on a backpack, fix it. Pocket rips, fix it.

I started sewing because I wanted to make a Guybrush Threepwood costume for Halloween. I'm currently making a bag and the next items in the pipeline are a couple summer shirts and a custom cover for a camera lens I have. I also brought my sewing machine to a kid's birthday party to make small plushies with the kids.

I've also repaired a non-insignificant number of clothes from friends and family. I know I used to roll my eyes when people used terms like "upcycling", but I have to say that I've come around since.

Outdoor equipment, if you’re into that sorta thing. I didn’t know anything and I think my second backpack was nice enough to use.

Also laminated fabrics tend to be much easier to sew since they are so rigid

I made a hat - an old one was getting threadbare so I used a seam ripper to take it apart, drew around the parts onto new fabric, and sewed the parts together. The brim was a bit tricky and the stitching isn't super straight because of the thick canvas (also, I wish I'd made it out of thinner material) but I get a kick out of saying I made it!

Most of the things I've made are probably bags and covers or other containers for things. You can make the designs very simple with some thought and bespoke sizes are often useful and impossible to buy.

Upholstery would be really interesting, but it seems that materials I would like (tough, not plastic) are essentially impossible to find here. And I'm often tempted to see if I could make some simple plain clothing because it seems that the shop selections just keep getting worse every year. Either that or actually find myself a tailor.

Bags, wallets, etc are quite fun, and you can find lots of options from the easy "two rectangles and a handle" to some clever backpacks and custom bags to hold specific items.

It is quite cool to have a bag with custom pockets designed specifically for the things you actually own and carry often, in the color and fabric _you_ like.

Clothes are harder as you need to learn how to fit them. But doable.

And pattern construction (aka "drafting") is a whole separate engineering discipline. Check freesewing.eu for inspiration.