A pictoral version of the one I mentioned on Podcast #22.
9. Homemade guitar made of a shoebox, rubber bands, and paper towel roll (tissue box and a few flimsy wood pieces like as shown above can count too)
6. Candles (There was an episode on Saturday Night Live in its early years where a guy would bellow out the song Smoke Gets in Your Eyes by placing his hand over different lit candles, resulting in an "ah", maybe "ow" in a different pitch)
5. Jaws Harp
3. Coke Bottles
2. Hawaiian Nose Hum (George Carlin makes mention of this in his 1972 Class Clown album)
AND THE NUMBER ONE LEAST POPULAR MASS INSTRUMENT (besides guitar):
1. Schroeder's Toy Piano