I pinned a sewing machine cover tutorial long ago, then finally felt inspired when I picked up a couple colourful fat quarters with cute bird and owl patterns. Oddly, it turns out, it's the same fabric as used in the tutorial. You'd think I purposely got fabric that matched the crazy wall colour, but that was accidental too.
I made all the measurements and cut out the fabric, which required a fair bit of tedious piecing since I was working with fat quarters and then I figured while I was piecing I might as well make it interesting. But then I left it part way done, I think because I was afraid I made a math mistake that would only become apparent when I put it all together.
Today I summoned my courage to finish the cover and against all odds it fits perfectly. So another happy accident! (I know I measured, but really it is amazing it worked out.)
I'd definitely recommend this tutorial. It's well written with lots of pictures and the trick for the corners sure is nifty.