I got a full set of steel stamps on e-bay many years ago. They were described as 1/4 inch, but they are a bit too big, and 3/16 are a bit too small. I think 7/32 would be close, but don't know if that size is made. These stamps may be identified with printers' sizes, aka point, which is a 72nds of an inch (1/4 inch = 18 point, 16 point may be the one). The "star" stamp is very difficult to find, although I imagine that "certain" restorers have methods. As you are in California, don't get caught.
Jim