Convert STEP/IGES files to STL on Mac

We’ve added a translator on Workbench that allows users to download a CAD file in STEP, IGES and STL formats, regardless of the format it was uploaded in. This makes it easy to share models with partners who don’t use the same CAD system you do.

With just one click your supplier can download any of the neutral formats based on the original file you uploaded.

Answered with a tutorial: https://grabcad.com/tutorials/convert-step-iges-files-to-stl-on-mac

Don't know about a stand alone app, but the MAC version of MoI (beta, www.moi3d.com) can import STEP/IGES and export to STL

see something like that element, but I'm not sure
can you come up a different format
AccuTrans
http://www.micromouse.ca/

thanks all

CAD Exchanger runs on Mac and can do this job, as well as many others. Standalone GUI application or a batch mode console app or an SDK.
http://cadexchanger.com

I put up a free web based converter which will convert STEP and IGES files to STL format. You can find it at http://www.3DTransform.com.

try this:
http://code.google.com/p/heekscad/downloads/list

or this
http://brlcad.org/d/download