Watch the ultralight instructional DVD numerous times and read the directions/instructions several times. The more you study the plans, the easier the construction becomes.
Concentrate on the airframe construction first. Follow all assembly instructions. Many ultralights use a combination of metal frame, reinforced fabric like mylar or a carbon fiber shell. Begin with the frame, and add the fabric or carbon fiber panels after constructing the frame.
Assemble the engine, or if the engine comes prebuilt, hang it on the engine crane and place it through all necessary safety tests. Consult the Federal Aviation Administration's current rules and manuals to bring the engine up to the legal requirements. The FAA-AIM is updated yearly; be sure to have the most current set of regulations when assembling the engine.
Wire the controls and instrument panels onto the airframe according to the ultralight kit's instructions. Mount the engine onto the ultralight and finish the assembly by adding the rotors onto the power plant on top of the helicopter.
Hire an inspector or certified helicopter mechanic to inspect your work prior to test flights. Helicopters need redundancy safety checks due to the complexity of their designs. Undergo all FAA helicopter flight training before attempting any rotor aircraft flights.
