[Mac OS X QuickLook](https://developer.apple.com/library/mac/documentation/userExperience/Conceptual/Quicklook_Programming_Guide/Articles/QLUserExperience.html) supports the Collada interchange format with `.dae` file extension out of the box. 

There is [CaniVIZ 3D Preview](http://www.caniviz.com/caniviz/caniviz-3d-preview-en.html) available for 59$ and there are free standalone viewers for CAD/3D files like [eDrawings Viewer](http://www.edrawingsviewer.com/ed/edrawings-mac.htm). There’s even a [plug-in for `.stl`](http://www.thingiverse.com/thing:376361) files popular in 3D printing.

Is there a free or cheap (< 5 USD) QuickLook plug-in, maybe part of a viewer application, that is capable of formats like `.dxf`/`.dwg`, `.3ds`/`.max`, `.obj`, `.skp`/`.kmz`?

How hard would it be to write or adapt an existing one? SketchUp/3D Warehouse `.kmz` files, for instance, are `.zip` archives that contain a `.dae` file among other stuff.