Here's a photo I did today. It's an 11X14 pinhole with a 127mm focal length. I shot it on an albumen glass plate negative with a 1 hour exposure time, and then did a contact print on another albumen plate, developed normally in gallic acid, and painted the back of the glass white.
It works, but it aint no ambrotype...
The actual photo is not quite as sharp and is a little lower in contrast, and the scanner I used can't quite get an entire 11X14 so some detail around the edges is missing. Also, when I enlarge the scan there are a series of lines in the upper left hand corner that aren't on the print.