# Wish list for an additional type of extrude

Maybe there is a way to do this with another command. After reading the post regarding Voronoi patterns I worked up this model. I created a flat pattern and then constructed a cylinder with the exact same area. Used the flow command to transfer the flat 2D pattern to the cylinder. now I wanted to extrude the curves as surfaces to trim and creat the open spaces on the cylinder surface. It would be great to have a polar surface and solid extrude option. This way a set of curves could be extruded perpendicular to the cylinder walls. I ended up deleting the inner cylinder wall and create this example by drawing a line from the cylinder center to a quad on the outline curve. Then simply copied the curve and use move command to snap it in place along the perpendicular curve. Polar extrude would allow me to select all of the curves and then select a axis curve located at the cylinder center and have them extrude constrained to the X and Y axis. Kind of like a mass extrude to a point command or extrude to a reference axis.

Not sure it would work, but my first thought would be to use the flowed pattern to trim the holes in the cylinder, then offset the cylinder with the holes using the solid option.

http://docs.mcneel.com/rhino/5/help/en-us/commands/offsetsrf.htm

Try the Fin command for the specific case of the curves are on a cylinder…

To create a “polar extrusion” with the center axis parallel to the z-axis:

1. ScaleNU with Copy=Yes the input curves.
a. Base point at x,y along the center axis. z value of base point does not matter.
b. x scale factor and y scale factor are equal and based on extrusion length from the curve relative to the distance of the curve from the center axis. Scale factors greater than 1 to extrude away from the axis. Scale factors less than 1 to extrude towards the center axis.
c. z scale factor=1

2. Loft between the input curve and scaled curve.

To create a polar extrusion from an input curve to a center axis parallel to the z-axis:

1. SetPt
a. Select the input curve
b. Check Set X and Set Y. Do not check set Z. Click OK
c. Copy=Yes
d. Enter x and y coordinates of center axis.

2. Loft between the input curve and line at the center axis.