So after making the heart-shaped pot holder mitt, I decided to go more basic, and just make a flat pot holder, also can be used as a trivet. I had some polka dot material and a ruffly border, and decided to stick with the theme of hearts.
With a little patience and diligence, anyone can make this! I started by tracing my heart pattern (used from my first mitt) onto two pieces of fabric (could be matching or different). Then trace the same shape onto your batting (again, I used Insul-Bright for heat protection, and just one layer) and cut all of your pieces out. Since I wanted to use my ruffly border, I decided to do the inside-out method for my edges rather than use bias tape, to make the edges look cleanest.
So sew your ruffly border onto the RIGHT side of your bottom layer of fabric, with the end of your ruffles on the inside (picture yourself turning it inside out at the end, and you want your ruffles to stick out). I started my ruffles at the top of the heart, not sewing too close to the middle, because that's where I'd make the flip. So once you've sewn your border all the way around your heart, take your top layer of fabric and lay it right side DOWN on your existing heart (which is right side UP). Now sew around the border, connecting the two layers of fabric and sandwiching your ruffles, but stopping at the top of the heart. (Sorry I don't have play-by-play photos!)
You should now have a heart-shaped-pita-pocket-like creation. Turn it inside out, so that now your pretty fabric shows on the top and bottom, and your ruffles stick out all the way around. Insert your pre-cut heart-shaped Insul-Bright into the slot you left open at the top of the heart. Make sure it lays flat, cut more off edges if necessary. Then fold over your fabric edges (for a clean look) on both sides of your heart at the top, making sure your ruffles line up, and sew through all layers of the pot holder to seal your opening. Then continue this sewing line (maybe 1/8" from the edge) all the way around your heart, like a border.
Lastly, if necessary/desired, machine quilt your heart to keep the three layers (fabric and batting) perfectly aligned. I chose a heart shape, but you could do squiggles, diagonal, horizontal, or vertical lines. Just sew with your fabric flat, making sure not to sew it into a bunch!
And, voila - a beatiful heart-shaped pot-holder-trivet!