I found the mold on Robert Eisenstadt's web site.

TRI-BAL (a/k/a 3 DOTS & DASH, and TREY-BALL) -- 3 balls and a long dash, repeated four times. 1929-1939. Joe Treybal Sporting Goods Company, St. Louis MO.

http://www.antiquegamblingchips.com/cmolddesign_geometric.htm

Dates look right... guess its still a streach though - but fun to think about...