Combine margarine, corn syrup, sugar, peanut butter and vanilla extract in a large bowl and beat at medium speed of electric mixer until smooth. Gradually beat in flour until well blended at low speed.

Chill 1 hour or until easy to handle.

Preheat oven to 350°F. Roll dough into 1-1/2-inch balls. On smooth surface, roll dough into 8-inch long ropes. Shape ropes into desired letter directly on ungreased cookie sheet.