Here is a link to the template Jeanne mentioned:
http://www.quiltknit.com/Fun-Patch-T...Me_p_2469.html
Edit: Oops. Just noticed the template is out-of-stock and I'm not finding it elsewhere.
I'm trying to figure out the template's proportions. Looks to me as if the long side is 5", bottom side is 3-1/2" and the short side about 2".