requirements for making a valid 3D printable part. The basics are these:
1. Construct the curve forming the shape of the part (I use 6 points and an interpolated curve.)
2. Use this curve to make a Sweep1 surface
3. Extrude a small square along this same curve to make a make a square-shaped ridge and cap it. (I've tried triangles too.)
4. Make a circular Curve Array of 3 specifying the number of ribs you want. Be sure to use a rail curve that matches the sweep curve in 1.
5. Twist these ribs a specified # degrees, and then twist them the same number of degrees in the opposite direction.
6. Join 1 & 5 and you're done - almost. As I said, the top of the part will be flat, so I add a small circular cone to make it come to a nice point.
For 3D printing I had to give the basic surface thickness so I could control the amount of light transmitted through it, and also to eliminate naked edges, so Step 2 is actually more complicated than I indicated above. …