http://activesolid.ncf.ca/asdpro.html
About ActiveSolid: ActiveSolid Professional freeware is a dual mode (both
end user application and ActiveX control) 3D modeling, mark-up and
visualization application. The entire application including its user
interface can be embedded inside Microsoft Office and Internet Explorer. It
features an intuitive GUI, import/export plug-in architecture (with
import/export plug-ins downloadable from ActiveSolid's home page), unlimited
undo/redo, associative 3D linear/angular/radial dimensions, robust Boolean
operations on 3D meshes, 2D polygons and voxel models (using linear
octrees), 2D profile generation, polygon offset, local vertex/face editing,
optimal solid reconstruction from parallel contours, extruding along vector
or a polyline path, view mark-up tools including interactive view clipping
planes, and an array of other powerful 3D object creation tools. Supported
file formats include STL, DXF, Q3BSP, XGL and various 2D bitmap formats.
Cheers,
Dan