Building a mission model
This could be a mission model as in the FLL 2016-2017 Animal Allies competition, or you could build one yourself. It should be about 1.5 the height of the robot, or even higher. Building the mission model is up to you. Use the parts that you have.
Using a box or other objects
If you do not have enough parts you could use one of the Mindstorms boxes. Just put it over a few books to make it higher.