Bullauge is German and means in English bull's eye resp. porthole.
When I tidied up my tool shed I found an old, big flashlight with a broken rechargeable battery.
Quickly I had the idea to use the glass and the plastic frame. I dismantled the parts and searched in my wood shed for a good piece of wood which should be the background.
I sawed the wood and drilled in the plastic frame and the wood holes for the screws.
Today I put the picture "old rose" in the BULLAUGEN PICTURE FRAME: