You should be able to get off cuts of any lighting gel or used filters from any theatre nearby. You’ll need to ask for a range of hues but otherwise there’s an abundance of packaging wrapped in transparent colours if you look. The beauty of using something transparent is that you can use it for mobiles to stained glass window effects either on your window or as a greetings card.
You don’t even have to be that precise about the arrangements you make and you can overlay quite a few colours at a time. I’ve gone for abstract images but you might prefer a figurative subjects instead.