I had several people ask how my scalloped round card for CPS Sketch 66 was made, so I made another card and took some pictures for you. Hope this helps!
First, I measured across my largest Spellbinders large petite scalloped circle die at its center point (measured its diameter). It was 4" across, so I knew that to get a gate-fold card that was hinged on the scallops, I would need to cut a piece of cardstock slightly smaller than double the width of the die-- 7-7/8" x about 4-1/4". (The same principles work at any size. If you are using a Coluzzle circle template, measure your circle, then cut your cardstock about 1/8" less than your circle diameter if you want to have a gate-fold hinge.)
My cardstock was scored at approximately 1-15/16" in from both sides. You can see the score marks in the picture above.
I folded both flaps in, making sure that they met in the center, and making sure that the die edges extended slightly past the cardstock on both sides. (You need to keep a small area on both sides uncut so that you have hinges when the card is opened. Think in terms of a paper doll chain--remember that you left their hands and feet uncut on the edges so that when you unfolded them, they would be connected?) It also helps to tape the die in place or use your magnetic mat. I tend to work a bit better with tape.
This is my card base and card front after cutting. Notice the hinges? The card mat layer is made with the largest plain circle die.
Now, to get the front mat layer cut perfectly, I closed my card and applied adhesive to only one side. Then I made sure my mat circle was in the center of my scalloped circle. Only the left side is attached here. I can now see exactly where I need to cut in order to have a perfect connection.
After cutting the front mat layer, I attached it to the right side. This is how my card will open. My focal image will not be split, for obvious reasons. I'll use a little button as a handle of sorts. I am also adding a layer on complementary striped paper, cut with the same circle die.
Ink: Tuxedo Black Memento by Tsukineko
Patterned Paper: Die Cuts with a View Nana's Nursery (girl version)
Cardstock: Neenah Solar White for the card base and PaperTrey Stamper's Select White for the focal
image (The Neenah is a bit thinner than the PaperTrey, so it's easier to cut a double layer. I like having a thicker cardstock for my focal image though, especially since it opens independently rather than being attached on both sides to a mat layer.)
Accessories: Pink Satin ribbon by Stampin' Up; Buttons by Autumn Leaves/Foo-Fa-La
Markers: Copic by Imagination International