Looking for cube ideas

[drawbar]

Hey all,

I've been trying to think of new things to do with my little CNC router. And one of the things I've seen before is a cube that has been cut into on all six faces, with something left over to float around captured inside the cube, like a sphere or something else.
Does anyone have any code, drawings, pictures, etc. they could share to give me ideas? I use AutoCAD for CAD, DesKAM for CAM, and Mach II for control.
In the download section, I've downloaded an IGES file that was described as something like this, but I don't have any kind of importer or converter for .igs files.

Brian

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http://www.sherline.com/CNCproj.htm