There are multiple pre-made tubes that can be used to create the airframe of your rocket. Below are some of the common ones and when to use them.

Cardboard Tube

Cardboard tubes designed for rocketry are thicker and have special coatings compared to a traditional cardboard tube. They are very low cost and available in a series of nominal sizes. In addition to being used for airframes for L1 and some L2 rockets, is commonly used as the motor mount tube for all sizes of high-powered rockets that have an independent thrust plate. 

Cardboard tubes can be easily cut and shaped, and even can be put into a laser cutter to create slots for things like fins.

A common supplier of cardboard tubes is LOC Precision. 

Blue Tube

Blue tube is a special airframe made of phenolic resin and thick paper or card stock. It provides better resistance to damage as compared to cardboard frames, but it is still just as easy to work with and much less expensive than other high-strength airframe materials. It is most often used for L2 and some L3 airframes, as well as the motor mount tubes for L2 rockets that do not have a thrust plate.

Blue tube cannot be laser cut like cardboard, but it can be cut easily with hand tools.

Blue tube can be purchased from a series of resellers, and is designed and manufactured by Always Ready Rocketry.

Fiberglass Tube

Fiberglass provides significant strength to your rocket and is used for large L3 rockets. Fiberglass tubing is significantly more expensive than the previous two options, but provides a very strong rocket material at a very light weight. Fiberglass tubes are composites, and need special care for working with. Special tooling, ventilation, and PPE must be used when cutting fiberglass, and the edges must be sealed or they can cause glass splinters in anyone who touches them.

Fiberglass tubing can be purchased in nominal sizes from Apogee Rocketry.

Carbon Fiber Tube

When fiberglass is not enough or too heavy, there is carbon fiber. Carbon fiber is stronger and lighter than fiberglass, but considerably more expensive. Like fiberglass, they require special care when working with. Carbon fiber tubes tend to be much more expensive than all the other options, and also have the challenge that they may not be RF transparent, meaning you may not be able to communicate with radios inside the airframe, like tracking systems. Usually sections of fiberglass are left in the airframe around avionics to prevent this issue.

A common supplier for carbon fiber rocket tubes is MadCow, however they can also be manufactured on campus using the X-Winder. See the Carbon Fiber Body Tube Manufacturing page for more details.