A puzzle card is a pretty simple to make. Instead of designing one card at a time, design as a set of 9.
Choose a design that can be cropped/resized to 2250 x 3150. Place that picture onto the 9 card layout sheet and you've made the front of the card.
For the back you can either use another 2250 x 3150 picture or make them individual designs for each card. Place these in the desired order on another layout sheet. If you choose to number the cards, remember you are looking at the back, right to left, top to bottom.