On this page of the game guide to Borderlands 2 you will find a detailed description of the side mission titled Positive Self Image. You can begin this quest in The Dust after you complete the main mission named A Dam Fine Rescue, in which you collect parts from the vehicle of the Bandits.
1) Ellie's workshop
Speak with Ellie in her workshop  to accept this mission. Your task will be destroying Bandit vehicles driving around the area. From their wreck you can collect Ellie Ornaments (screenshot). After gathering six of them, return to Ellie .
Now place the figures in the designated places in the middle of the workshop. When you do, speak with Ellie to end the mission. As a reward you will receive a Relic which enhanced Boost in vehicles.