(I totally made this up.)
I wish Mrs. Weasley had some of these knitting inventions on the market! It would make knitting so much easier and fun:
Knitting Needles:
1. Needles that are self-measuring needles (both in the length of you knitting as well as side to side).
2. Needles that automatically count your stitches and set off an alarm bell when the incorrect number of stitches is on them.
3. Needles with charmed points that worm their way into multiple or tight stitches (like in a 7-stitch nupp) and then snap back into a rigid state when you finish the stitch.
4. Needles that continue knitting your harder-to-knit project correctly at knitting group while you work on plain stockinette stitch and gab and eat and drink.
5. Needles that you can pick up for mindful knitting, that don't really make anything, just rows and rows of stockinette stitch, which then unravels itself and winds up the ball when you are done thinking about the problem and put it down.
Other things:
1. A finder to run and go find your pattern, find that one ball of yarn you need from your stash, find your tape measure/scissors/pins, or find the glasses you left on your head.
2. A little being like the Quidditch ball that can go to whomever you need the measurements of, takes the measurement, and reports back to you. Also operates in stealth mode, for Christmas presents.
3. A special yarn additive that can make sleeves or body or fingers longer or shorter, body wider or skinnier in the right places, and also sends the information back to the self-counting-stitches needles.
4. A clock that lets you stop time for an hour so you can just knit or crochet. Works over and over and over again.
5. A special page illuminator that makes perfect sense out of a pattern instantly.
6. The pattern for this fantastic top (I couldn't find it on Ravelry, go figure):

I could go on, but those are fresh off the top. What inventions would you like to see from Mrs. Weasly?