Conversion from Powermill to Rhino3D is not supported yet :(

Powermill is a 3D Computer-aided manufacturing app developed by Autodesk Inc. It runs on Microsoft Windows and is used in many different engineering industries to determine optimal toolpaths to reduce time and manufacturing costs.

Powermill rapidly creates toolpaths on large, complex parts, works with surfaces, solids and STL meshes. It uses efficient roughing strategies and can create gouge and collision free toolpaths, which can be edited and optimized. The software obtains comprehensive range of finishing toolpaths, user-defined macros and templates for automated CAM, extensive library of tool types for use with 3- and 5-axis milling, and specialist tools for demanding industries and applications.

Rhinoceros (typically abbreviated Rhino, or Rhino3D) is a commercial 3D computer graphics and computer-aided design (CAD) application software developed by Robert McNeel & Associates. It is used in industries including architecture, industrial and product design, in multimedia and graphic design and runs on Microsoft Windows and OS X. Rhino uses Grasshopper, a visual scripting language add-on, developed by Robert McNeel & Associates.

Rhino is based on the NURBS mathematical model, so it focuses on producing precise representations of curves and freedom surfaces. It allows users to create, edit, analyse, and visualize NURBS curves, surfaces, solid bodies, point clouds and polymeshes.