This 3 inch float has a simple 'roof' mark (with no other symbols) stamped on it.  The roof is flared at both end.  I haven't seen this mark in any reference books, so I assume it's undocumented.  I have heard that there are other examples of this mark, though.

This appears to be an 'old' float due to its crude construction.  It's out-of-round and quite heavy for its size. 

There are also thousands of bubbles in the glass.

This particular float was beachcombed by Paul Umlauf along the coast of the Aleutian Islands in Alaska.