Melanie, Kate - there is one exception. I've enjoyed the fact that I was challenged to use Bryce; I have it, but have done very little with it. Open challenges should not require ANY software (heck, they probably shouldn't even specify 2D or 3D, except when it's something like Mallo's "redo my 2D work into a 3D image" kind of thing), IMO, but for Triangle Challenges, anything goes, as they can be specifically targeted at a person with the proper software to do it! :-)