The first type of jetpack, worn by the Blue Robot, is dark grey with a white and black antenna in the center and twin nozzles at each side. The nozzles and the tubes they come from are much like standard blasters in design. It's possible that the jetpack was made from two modified blasters attached to a power cell.
This type of jetpack is light grey with two large black tubes attached on each side. The tubes widen near the bottom and are known to spurt light blue flames when in use. It is used by the Red Robot.