...
In short, you must safely launch a rocket on a H or I motor and recover it in a condition such that it could immediately fly again to get your L1. The rocket must have been constructed entirely by the person going for their certification, and they will usually be asked a series of questions about the construction techniques used by the RSO at the launch. In order to make a safe flight as described, the rocket must be stable and strong enough to withstand the thrust of the chosen motor, have retention to hold the motor into the rocket during coast and recovery, and have a working recovery system.
Documents
NAR L1/L2 Form (includes checklist)
Examples
<People should post some pictures of their L1 rockets here>
Any rocket that meets these relatively open-ended requirements can be used to gain your L1. Some people fly a minimum diameter carbon fiber 38mm rocket on a large I to over 10kft to get their cert, while others send a 6" cardboard rocket to less than 1kft on a mid-sized H. Experienced fliers will likely already have an idea of what they want out of their first HPR, but newcomers might have a harder time selecting an appropriate design. For that reason, the team has a standard design for an L1 rocket that will get around 2kft on economical 29mm H motors, perfect for fields near campus. The rocket is constructed from 3.0" cardboard LOC parts, and all of the required components can be acquired for under $30 per rocket. Builders of this design are free to customize the fins of the rocket to their liking, as long as it is still stable. A boilerplate openrocket design for a good L1 rocket is located here.
...