I have a lot of cow bells. My favorite will start “Cowbell of the Week”. This will be over when I run out of cowbells.
The rest are all promotional ones. Figured I should start with the best.
I picked this one up at a “hardware” store in Switzerland on a good tip from a great friend. The local color in the store was worth the trip. The cowbell was a nice added bonus.
While there I was able to buy some beer, a few groceries, and had the possibility of several garden tools. (I passed on those)
This has great sound and was formed out of a solid piece of metal, then brazed together. See the side view. 
Kinda makes me miss cross season.