So this one is fun and easy.  I started collecting all sizes of jars.  The big one is pickle jar and the smaller ones are spaghetti sauce, pickle, and jelly jars.  I just went to Dollar Tree and bought a collection of things to put in jars.  I added water to some and even dye to give a gross effect.  My jars contained fingers, spiders, eyeballs(gum balls) and a big hand.  I put these in my kitchen window so they could be seen from outside also.
Conclusion: The kids loved this one. Easy and cheap to do. I emptied out the water to save for the next year.