Experiment 1A: Participants either inspected an IKEA pre-built box or assembled it themselves. Afterward, they were asked to bid on the box they had either seen or built. If their bid was above a random number, they would pay that amount to keep the box; if it was lower, they couldn’t keep it. Participants were also asked to self-report on the value of the box. An effect was found in both cases; on average, participants bid 62% more when they built the box versus when they simply inspected it. On average, participants also self-reported liking the self-built box more than the inspected boxes.
Other experiments used origami creations and LEGO sets, and the same effect was noted. Read more about it at NeoAcademic. Link -via Boing Boing