Years ago I made this article about upscaling my kids small plastic animals and other funny thing. Collect a big pile of mini toys that your kids will not miss or will give you an ok to use. Take the selected frame and place all the figures the way you like — take at picture to remember the "pattern". Spray paint all the figures.
When dried — glue them to the canvas with a glue gun, and you will end up with a modern art peace to give someone, or put on the wall.