No. Our boxes hold 300-400+ pieces of flat art, are 24x18x4, and you CAN combine different kids’ art or art for multiple books/mosaics in the same box as long as it’s separated by child and age/grade (if relevant).
There is no need to purchase more boxes than you need, as the 2nd payment you'll make is based on the number of pieces of art you send and number of books you want, NOT the number of boxes you order. Most people find that one or two boxes is more than enough to accommodate all their art.