In Blender 3D, there is a circle select tool (formerly brush select) that allows you to paint your selection as if using a brush in Photoshop. After extensive searches, I can't find anything like it in Autocad.
Is there anything like this out there already, or will I need to draft it up myself? Any tips on how to do it would be awesome. Is there a tool that lets you click and drag to dynamically create a polyline or spline (sort of like a fence select where you hold your click)? I could possibly hack together some code onto that to offset the line with circle end-caps, and then select within curve.
The Blender circle tool is demonstrated in the second half of this video:
https://youtu.be/WCTuc2Dk-3E?t=2m10s
And it's documented here, under circular region:
https://www.blender.org/manual/modeling/meshes/selecting/basics.html