This is a Universal Fin Can for Model Rockets, particularly Water Rockets. These fins are printed using "vase" mode with the end caps disabled, to create the hollow cylinder with fins that you slide onto your rocket. Since the model is 100mm in diameter, you can scale it to fit any diameter rocket by putting the diameter in mm as the scaling percentage in your slicer. That's that makes them universal!
Run a test print of a few layers and then stop the print and take the partial piece off the printer and test fit it to your rocket. Tweak the scaling factor until you get a perfect fit. Then use that to print the entire fin can and slide it on your rocket.
Learn more about printing this design in our YouTube video explainer: https://youtu.be/2L9sUAmevzc
Read the instructions for this print or learn about Water Rockets in more detail on our website:
Use vase mode to print a single wall extrusion with the top and bottom disabled. This model is exactly 100mm in diameter, so you can measure your bottle and scale to fit by putting your bottle diameter as a percentage in the scale factor of your slicer.