1. Create a tube with 8 segments.
2. Select the opposite edges and move them up to make a sort of a wave silhouette.
3. Bevel the edges.
4. Use radial array, make 3 copies and then rotate it.
5. Turn on the modifier, select the last object and then move it up.
6. Bake array and smooth object.
7. Choose the color and material you want to be applied.
8. Export the .stl file.