Recycling trading cards into coasters isn't something new, but it's something I wanted to try my hand at. I didn't like the idea of taking a trading card and slapping it onto a square tile since I found that to look pretty ugly (to each their own, I suppose). So the exercise here was more of a "graphic design" one, where the importance was emphasized in turning a rectangle image into a square.
Simply cropping a trading card to be square wouldn't work as it would be too small for a mug (~2.5 inches for the short side of a trading card) and you'd likely have a strange uneven crop with some graphics missing.
I came upon two solutions I liked:
1. When using standard trading cards, the back side of the card will typically have some kind of pattern or non-repeating graphic that would frame the actual card quite well. In the case of the WWE cards, the copyright information was perfect to use as a frame. Find two other cards you don't care about and cut away.
2. When using CCG/TCG cards, lining up three cards in a row, as if looking at a small hand, looked really nice. The hard part with this is cutting the cards as CCG/TCG cards typically have rounded corners. Find two other cards you don't care about and try your best to x-acto your way around the rounded corners.
The most important thing is to cut the frames to compliment the card you want showcased as the coaster. It's also important to line it up properly, taping the back, and then using something like Mod Podge to seal the top. While you could just line up a few cards together and glue them together, you lose one of the most important aspects of a coaster: it being flat.
After you have a nice square coaster, you can either reenforce the back with hobby sticks (like I did in the photos) or now mount it onto some kind of tile or cork board.