Here's what I did:
Every time I make a mat, I take the larger layer and subtract a quarter inch. So, in this case the green base is 4.25"x5.5" then the blue would be 4"x5.25" followed by the patterned paper from Basic Grey which is trimmed to 3.75"x5". I used Bazzill 5mm Hershey brads in the corners. (Make sure you put brads and other embellishments that require you to go through a layer of paper on before you adhere your design to your card front. You don't want the person receiving your card to see your brad's behinds on the inside of your card. It's just not pretty!) When I'm done putting brads through my paper I always smash them down on a hard surface to make them super flat. It really keeps the paper from being lumpy. The inner blue mat is 2.75"x4" and the center green piece is 2.5"x3.75". Before I layered the green onto the blue I printed my sentiment on the green card stock using Monotype Corsiva at a 20pt bold font. I tied some beige ribbon to the front and used a ruler as a guide for the paper piercing. After assembling all of the layers I then glued it to the green standard A2 card. I used the same font and style on the inside of the card to finish off the sentiment. It says: "Don't get too excited though we have a special day for groundhogs too!" And...that's it!