I was a builder on all four of these costumes, and more.
A little about these characters:
When entering the Training Center, tributes were required to enter viachariot rides that would show the audience what to expect from the competitors of each district. The chariots would be decorated according to which district they belonged to and their district's industry. Most of the time the audience would cheer for the chariots they liked and do nothing for the ones they did not like. The chariot rides were very important because it was a chance for the tributes to make an impression on the citizens of the Capitol and potential sponsors. Most tributes, to make a good imression or the audience like them, would smile and wave and appear friendly. This is also the first time the Capitol gets to see the tributes, so a good impression is very important in order for them to receive sponsors.