I realized suddenly at the beginning of a project how spoiled I have been by the ease of finding templates online for any shape I could ever need to make. Just print and trace or cut out...without ever giving it a second thought. Hearts are particularly easy - I can just use the heart shape tool in Photoshop and stretch or squash the heart to the right dimension and enlarge or reduce the size until it's just what I need, and print it out.
However, what happens when I need a HUGE shape - too big to print out? Hmmm, do I trust myself to be able to draw a perfectly symmetrical heart on a piece of posterboard? Uh...no. So I came up with a plan.
Here's how to draw a symmetrical heart without a heart-shaped template to trace!
I am using a rectangular piece of foam posterboard, but these steps will work for a square board as well, since the heart is symmetrical and equilateral. My finished heart shape is about 20 x 20 inches, but this method can work for other sized hearts using different round objects to trace depending on the size you need. I used a pencil to mark my lines but since they barely showed up in the photos I have redrawn them with Photoshop so you can actually see them :)
First, use a ruler to measure and find the midpoint of the short side of the posterboard. Mark the midpoint at both ends of the board, as well as in the middle, and then use the ruler to line up all the marks on the edge and draw the line down the middle, longways.
Find a round object that you can trace that is roughly the same width as half your rectangle. In my case, a 9" pie pan was perfect - the diameter of the top edge of the pan is about 10" across, just less than half my piece of posterboard. NOTE: you can also use a compass to draw your circles, if you have one.
Trace the object on each half of the board, keeping the top and bottom edges of the circles lined up with each other, and both touching the midline at the same point.
I used the ruler to draw another line below the two circles, all the way across the posterboard. The point where the vertical and horizontal lines cross represents the center of your heart shape. In this case, since my circles are 10 inches in diameter, I measured 10 inches down from the center of the heart where the lines cross and made a mark. I used that mark to line up the ruler and draw a straight line connecting the bottom point of the heart to the circle on each side, near the midpoint of the curve in that little corner formed by the lines.
That's it! I used a sharp craft knife to cut out my posterboard heart...
...and I used it as a base for my crepe paper rosette covered heart frame photobooth prop.