01-28-2019 05:37 PM - edited 01-28-2019 05:38 PM
This was purchased in the early 60's along with a part that came from WW2 plane most likely. It may have been from a military surplus yard in the San Francisco Bay area.
01-28-2019 07:32 PM
it is the shape of a lamp cover as used at airports and shipping buoys. looks awfully opaque though.
