How young is too young to let a kid use the sewing machine?

I taught my youngest at almost the same age, and the hand sewing with a big plastic needle and yarn is exactly where I'd start. Give him a square of felt or a piece of an old sheet, pre-punch the holes if you need to, and let him do a running stitch wherever he wants. It doesn't need to look like anything. Mine stitched a lumpy rectangle for a week and called it a blanket for her stuffed rabbit, and that was the whole project. Totally successful in my book.

The machine thing with you on the pedal and him guiding the fabric is a good middle ground too. Keep the speed slow and pick fabric that's easy to handle, like cotton squares with nothing slippery or stretchy. I'd trace a line on the wrong side with a pencil so he has something to follow, because steering in a straight line is the part that frustrates them. Expect wonky seams and let them be wonky. For project size, pillow is the sweet spot. A simple envelope pillow cover means no binding, which is honestly the fiddly part even for adults. He can pick the fabric, sew the front to the back, stuff it, and be sleeping on it inside a week or two. Small doll quilts are nice as well, but a pillow he can actually use feels like a bigger win to a six year old.

On attention span, keep sessions short and stop while he's still having fun, not after. Fifteen minutes at the machine, then done, and he'll come back tomorrow asking for more. That worked better for us than pushing thru untill a step was finished.

One practical thing, cut the fabric yourself and have the pieces ready before he sits down. Waiting while mom cuts is where a six year old loses the plot. Pre-cut charm packs are great for this if you have any lying around, since the squares are alredy done and he can just arrange and sew.

Agree with the short sessions advice, that was the whole game for us. I did the pedal-and-guide setup with my daughter when she was six and we kept a little calendar on the fridge where she got to put a sticker every day she sat down at the machine. Sounds silly but it turned sewing into something she looked forward to instead of a chore. I also let her dig through my scrap bin and pick her own fabric for the pillow cover, took her twenty minutes of agonizing and she was way more invested because of it. Three years later she still uses that lumpy pillow.

For the machine part, the thing that actually made it click for my grandson was a strip of painter's tape on the throat plate as a seam guide. He couldn't follow a pencil line to save his life, but tape gave him a bright edge to steer against and suddenly his rows came out almost straight. Cost me nothing and took ten seconds to put down. Also, let him do the seam ripping if a seam goes bad. Kids his age find it weirdly satisfying, and it turns mistakes into part of the fun instead of a failure.

I ran a junior workshop through my guild for five years, maybe 30 kids through it total, and the trick that kept the littlest ones hooked was the label. Once a kid finishes anything, even a wonky nine patch, sew a little fabric label with his name and the date on the back. Hand stitch it yourself if needed. They treat that square like a museum piece afterward, and mine bring theirs out years later to prove it.

Also let him do the planning part with you before any sewing. Have him draw the layout with crayons on paper first, then he can match fabrics to his drawing. A six year old with a design he made himself will sit a lot longer than one just following your instructions. And yes on the pillow over the big quilt. I'd add one thing though: buy the stuffing at the fabric store and let him scoop it in himself. For some reason that step steals the show every single time.

Following this because my niece keeps asking to try the sewing thing too and I have zero clue where to even keep the sharp stuff. One thing I keep wondering though, does the yarn and big plastic needle trick work on normal fabric or does it realy need to be that felt stuff? I pictured her sewing two squares of an old t-shirt together and I don't know if the holes would be too small for yarn. Also does the kid actually thread the needle themselves or do you do that part? Seems like threading would be the frustrating bit for little hands.

Update: tried the painter's tape guide trick and it made a huge difference, he steered way better once he had a bright edge to follow. Still fighting the attention span though, he's done after maybe fifteen minutes and loses interest fast. For those who kept the little ones coming back, how long did your sessions actually run?