One housing for a dynamo, and one for batteries.
I originally made the small one for the helmet but I was a little afraid of it over heating and smoking the LEDs. There is not a whole lot of metal on that one. I figure it should be okay for a dynamo light though since it is only ever on when the bike is rolling, and never makes more than 500mA.
You can see in the picture below there is considerably more material in the larger one.
Showed my wife a thing or 2 on the lathe. Here she is boring a housing!
Here's the little bandsaw that could! Needed some repairs over the past couple years. But boy is it nice to have when it works!