I am considering taking a photo mat onboard to drop off at GS for character signing. Any suggestions on what size mat to get and/or what size cut out for the photo? I am not sure how many Shutters photos we plan to buy this time so we may end up using a photo we take in the frame... that decision wont be made till after the cruise. I assume a white mat is a good choice and maybe place some painters tape around the edge? Any tips are greatly appreciated!