Fins for Water Rokit rocket kit

The Water Rokit is a great way to get started with rocket science and the fact that they sell spares is even better. However, if you don't want to wait for shipping, three copies of basic fin.stl can be printed in under an hour. It's similar to the original fins in shape and size but weighs more when printed in PLA, so you may need to add mass at the top of the rocket to ensure stable flight - you can see how straight it flew (or not) in the second image!

I've also included files that can be used for experimenting with different fin designs. The mount is designed to press-fit into the white screw cap in the same way as the original fins. Using the SVG import function in PrusaSlicer, you can merge the mount with a fin quite easily.

Creating custom fins for 3D printing

1. In the editor view, right-click and select ‘Add Shape → SVG’.
2. Choose mount.svg and set the depth to 3.0 mm.
3. Repeat steps to add the fin SVG; I used a depth of 2 mm.
4. Rotate the parts if necessary.
5. Select both parts, right-click and select ‘Merge’.
6. Change the drop-down box under ‘Part manipulation’ to ‘Object coordinates’ and centre the fin on the mount. Below are the settings I used to create basic-fin.stl:

Print settings

The examples shown were printed with default settings so there's lots of room for optimising both fin weight and print time (approx. 45 min and 35 g).

• Printer: Bambu Labs P1S
• Nozzle: 0.4 mm
• Preset: 0.20 mm Standard (Bambu Slicer) with no changes.

Material

The photographed versions were printed using some transparent PLA that I found sitting open in a disused toilet block so you could probably use any material. Good options might be something tougher such as PETG or perhaps lightweight PLA (PLA Aero, PLA-LW).

Slot and tab versions

These are provided in case you want to produce fins with a different method or material. One idea I had was using a 3D printed mount with laser cut balsa or cardboard fins.