The IKEA effect, named after everyone's favorite Swedish furniture giant, describes how people tend to value an object more if they make (or assemble) it themselves. More broadly, the IKEA effect speaks to how we tend to like things more if we've expended effort to create them.

This is the effect companies like “Build A Bear” where people can pick out materials to build their teddy bear or Restaurants like “Ghengis Grill” where you can pick the ingredient to be used for your food value it more.