I believe that "Alpacca" was one of many trade names used for a silvery alloy
most commonly referred to in the U.S. as "German silver", which was usually
not plated, but solid metal. It was marketed, often deceptively, as an
inexpensive substitute for sterling silver.
Sorry, I know this does not help you identify the designer, but it may be
helpful to know that Alpacca is probably not the name of the design, but of
the alloy.

John Vanco, [log in to unmask]