Kid sewing: Wizard hat for a penguin! OR, How To Sew a Fabric Cone for a Specific Size with Real, Accurate Math!!

C. had this whole idea to make a wizard hat for her penguin plushie, so I helped her make it happen! She designed it and sewed it herself. All I did was help take measurements and figure out how to cut out a fabric cone!

You MUST keep reading after the jump for hilarious pictures and the all-important CONE TUTORIAL!

Yes, it's also perfect for the cat!

To help humanity, I'm going to tell you how to calculate what you need to make a fabric cone (aka wizard hat!). (The internet is NOT HELPFUL in this regard so I had to do it myself.) First, measure the circumference (C) you want (this would be around the penguin's head). Then decide the height you want your cone to be, like how tall to stick up off the head.

Find your diameter of the base circle with C/3.14 (pi), and then divide that by 2 to get the radius. This radius measurement, and your height, are two sides of a right-angle triangle you next find the hypotenuse for. (Because that hypotenuse is the part of the cone that's actually swooping around and forming the cone, NOT the height! (so many stupid internet people know nothing...)) Here is your friendly reminder that to find the hypotenuse = square one side, square the other side, add them together, then take the square root of that. (For example, if one side is 3 and the other is 4, the hypotenuse is 5.)

So now take a big paper and mark a point. Tie a string around a pencil, and cut the string to the length of the hypotenuse. (Be sure to double check the measurement from the tip of the pencil lead to the point you drew.) Have your kid keep the end of the string on the point with her finger ;) and hold the pencil perpendicular to the paper as you inscribe a nice big arc, bigger than you think you'll need, but doesn't have to be a complete circle. Draw out a straight line from the point to anywhere on the left side of the arc.

Now maybe there's a more scientific way to do this, but I took my sewing measuring tape (held vertically!) and just measured off the circumference length along the arc from that starting line. At the correct distance, I marked and drew another straight line back to the point. Here is your cone!

BUT WAIT! Now add 0.5" for seam allowance on all three sides. The straight line sides will overlap when you sew the cone right sides together, and the bottom arc gets a nice hem.

I hope this tutorial helps someone, somewhere. I got so frustrated with everything I found online, so just know that this is accurate and will get you what you want, in a specific size!

We added in C's clever velvet ribbon tassel when she sewed it up. I showed her how to add it to the "inside" (and pinned it away from the seam) so that when turned right side out, it would neatly pop out the top! I love how it turned out!

We opted to add the sparkly ribbon trim after it was put together. I sewed down one edge and folded over the end neatly, then C. sewed down the other edge -- super neatly!

The hat fits the dog, too -- not that she sat still long enough to get any better pictures! ;)