At a Blend Bash, guests scoop and mix their own Sprinkles into a scent nobody else has. The catch is they'll burn through that custom blend and never remember which scoops they used — so a card with your name on it is how they get the exact same scent again.

You host Blend Bashes and sell online from a catalog of 50-plus fragrances. Drop a card in every order, printed on thick 16pt stock that takes a beating in a party bag, and a one-time blender becomes a regular.