I saw this exciting app tweeted by @palmyteacher. The app is coLAR Mix. The app itself is free and there are 9 pictures you can choose from in the free range. There are three simple steps:
1) download the app
2) select and print the pictures and colour them in
3) Go to the coLAR Mix app and hover an iPad, iPod or iPhone over the picture
Once your picture is 3D you can move the iPad around and the parts of the picture will move with it. You can also enlarge the 3D objects.