Rex used LEGO sets based on other time-travel media to construct a time machine .
Aboard his ship , Rex reveals that he is an embittered version of Emmet from the future ; abandoned for years underneath a clothes dryer after crashing in the asteroid field , he became Rex ( `` Radical Emmet Xtreme '' ) and to save his past self , constructed a remote time machine ( from LEGO sets based on various other media that involve time travel ) .
The Lego Movie 2-COLON- The Second Part