"R.H." wrote:

More photos have just been posted:

http://puzzlephotos.blogspot.com/

Rob
272 sliding window/door lock
273 lathe dog with fixed stud on face plate
274 ink, oil, or glue dispenser
276 camera iris or variable orifice
283 the open end may be for a different size of can.
it would follow the inside or outside of the raised lip.