It is marked near the bottom with the numbers 51, 11 and 12, no manufacturers mark. 3-1/4" tall by 4-1/4" diameter at the top, 4-7/8 diameter at the base, and is made from a substantial gauge of copper.
The mold is in very nice condition with character from age and use; I note. Some shallow dents or dings along top edge (see photos) but not severe or noticeable. Interior tin lining has wear and has darkened from use.
I believe the mold is circa 1890 period. Last photo shows some of the copper molds I have listed; this listing is for the swirl mold shown on the back left.Please enlarge the photos for details. Comes from a non-smoking home. Please message me with any questions.