Cutting Splines

[1350519287]

I was pointed to this article.
https://learn.adafruit.com/metal-parts-from-3d-prints/
I downloaded the files and thought this might be a challenge for AlibreCAM (VisualCAM). The perimeters and flat surfaces are pretty easy with a few different ways to skin the cat so to speak.
But how to do the splines. I find that selecting 3D machining and the inner and outer perimeter with a 30 degree tool creates open loops.
How does one go about setting up this kind of machining operation?
The file is too big to include so I've put it here: http://www.autoartisans.com/mill/locking_plate_01.zip

[MecSoft Support]

You can select the outer perimeter at the base of the 3d feature and use this as your containment region and program 3 axis roughing and finishing operations. Use the minimum radius in Radial Machining to contain the tool to the inner region. Alternatively you can create a circle for the inner perimeter and select this along with the outer perimeter to contain the toolpath. When the selected containment region (curve/edge regions) is not closed loop, this would result in an open loop error when programming 3 axis roughing & finishing operations.

[1350519287]

That seemed to work for generating G-Code. I'll try it out on the mill and see how it behaves. Thanks.