The only reference I have found to a pewter variety of the Washington before Boston medal is the reduced size medallion issued by the US mint 1974-1976 as part of a 15 piece set of historic medals produced for the bicentennial. It is listed in Russell Rulau and George Fuld, Medallic Portraits of Washington, 2nd ed., Iola, WI: Krause Publications, 1999, p. 60 at the bottom of the second column, where an uncirculated example is listed at $6.00. These are small size medalets (somewhat larger than a half dollar at 38.1mm, while earlier issues are much larger than a silver dollar at 67mm.). Earlier issues are usually in silver, dark bronze, yellow bronze, red bronze, white metal, copper and one example in gold. There are also several copies cast (rather than struck) in lead, some have been silvered.