If you are trying to make bellows or a speaker cone here is an easy way to do that.
I'm using the function plotter to make a sine wave pattern like I did in post #64 to make the shape of the bellows, first you make a rectangle with no fill:
![](https://infinityplays.com/content/images/2024/03/86-1.png)
Make sure it's selected and open the function plotter extension:
![](https://infinityplays.com/content/images/2024/03/86-2.png)
If you copy these settings it should give you a sine wave pattern like this:
![](https://infinityplays.com/content/images/2024/03/86-3.png)
Now you can delete the rectangle and rotate the sine pattern to make the side of the bellows:
![](https://infinityplays.com/content/images/2024/03/86-4.png)
If you drag the selection box you can adjust the size and shape of the pattern. Next I added any additional lines needed for the shape of the bellows. I am using the rotate extrude module of the svg import code I made in post #68 so all of the object needs to be on one side of the z axis, otherwise OpenSCAD will flag an error.
![](https://infinityplays.com/content/images/2024/03/86-5.png)
Once I'm happy with the shape of the bellows I can add nodes to the object and convert the extra nodes to lines then save the .svg file and import it into OpenSCAD:
![](https://infinityplays.com/content/images/2024/03/86-6.png)
![](https://infinityplays.com/content/images/2024/03/86-7.png)
Once I import the file I need to specify which layer the drawing is on in the rotate extrude module's layer name box, then set the number of faces and extrude degrees.
![](https://infinityplays.com/content/images/2024/03/86-8.png)
![](https://infinityplays.com/content/images/2024/03/86-9-1.png)
By adjusting the rotate and move settings many different shapes can be made:
![](https://infinityplays.com/content/images/2024/03/86-10.png)
This method can also be used to design things like speaker cones :
![](https://infinityplays.com/content/images/2024/03/86-13.png)
![](https://infinityplays.com/content/images/2024/03/86-12.png)
There are a lot of things you can make like bucket lids or interesting flower planters, the versatility of a drawing program like Inkscape combined with a customizable 3d program like OpenSCAD that are free and open source is pretty amazing.