I don't have 3DSM, but think that it will import .ai files. If so you can just draw it in a drawing program and import. In Swift3D you would just draw this in the extrusion editor, and 3DSM may have a similar tool.
Didn't look at the .png since you said you figured it out. For a sphere, check the 'hemisphere' option when the sphere is created. This allows you to create partial spheres.
The direct answer to 'cutting' away parts of object is to use Boolean compound objects. Boolean operations often leave artifacts that require substantial effort to clean up and they show up at render time. Use as a method of last resort.
With a little work on box modeling, you can create complex objects without having to resort to Booleans.
Splines can be used to create complex cross-sections with cutout areas that produce very clean extrudes. For example, I used spline and box modeling to create a helicopter and minigun. The barrel faceplates and crosshairs have cutout sections -- not a single boolean in either model.