LEGO.com runs a free affiliate program that pays a commission on validated sales you send to LEGO.com. Pinterest lets any Pin point to a destination link. Put the two together and every product Pin you publish becomes a small, faceless storefront: someone taps your Pin, buys on LEGO.com, and you earn a cut. This playbook walks through joining the program, building your first affiliate Pins, and staying inside Pinterest's and the FTC's rules.