These modules allow a payload bay to be used with the model rocket parts in my other designs. One specific use is to hold an Estes Model Rocket LCD Altimeter. The payload bay will firmly snap to a nose cone. The optional payload covers can be slid inside the payload bay tube to allow the payload to be fully enclosed, with two sizes to allow for either a loose or tight fit.

rocket with payload = stage + tube + payload + nose

My designs for other modular rocket parts are at:

https://www.thingiverse.com/thing:7011356
https://www.thingiverse.com/thing:7056020
https://www.thingiverse.com/thing:7024825
https://www.thingiverse.com/thing:7011337

The OpenSCAD file is provided here.