As I have said so many times, I love to create layered card fronts. This means that when it comes time to mail them, I have to go into the post office to see if I need to add additional postage due to the thickness of the card. I noticed that they use a card with a slot cut in it to measure the thickness of the envelope. I decided that I needed one so I could calculate my postage at home and save the trip to the Post Office. I have posted the link to it on the “Card Making” page. I cut it from Kraft Board. I hope this helps you measure the thickness of your cards and decide whether you want to add the depth and pay the additional postage.