A  Shoshone pine nut winnowing basket (photo from ISU 
museum). Its shape is specifically designed for the winnowing motion. We can think of the rim of the winnowing basket as a rose-petal shape, pointed at one end and broad at the other. The wild rose is an important plant in Shoshone culture.

A common way to make such petal shapes in mathematics is by graphing in polar coordinates. The polar coordinate system is very similar to the Shoshone basket-making technique: 

 Note that mesh inside the basket originates from the many struts attached to the pointed end of the petal. In the same way, the polar coordinate system always has the radius attached to the origin point.

Here is a polar graph of the function radius = cos(2*theta)+0.8. Shoshone basket makers have to figure out how long each strut would be for each angle theta, just as the function tells you the radius for each theta value.

The basket depth is created by having strut length longer than the radius across the plane of the basket rim.
Now lets make a winnowing basket! Go to the simulation window and experiment with the following parameters: 

length =_____
depth =_____
shape: s =_____ 
trim = _____
number of lines across width: n =____
number of across length: m =____

Use the mouse to change a value, then hit "enter" (you may have to do that more than once, check to see if the cursor is changed to an hourglass, if so just wait). 

Try to see how close you can get the simulation to look like the original.

Try to create a totally new shape of your own design.

To save the image, left-click on it and "copy."
Then paste into our collection. Don't forget to type your name underneath.