Here is a great DIY puzzle idea for you. Cut the paper rolls in half horizontally and put them on top of each other to form a whole, then create your image. Even your little one can create his/her own design. You can draw animals, patterns, movie characters.
Here is another cardboard puzzle idea for you. While matching colors and patterns, you can learn about symmetry, too. Very easy to make.
Another puzzle idea for toddlers. While learning about animals, you can make these puzzles, too.