I took the original large file holder and rounded out the back. Sharp corners seem to be a week point for my 3d prints (or maybe I expect too much, either way.) and I wanted a little spot for them to rest in so there is a slight divot in each hole. also, I wanted to slide it on the edge of my desk as in the picture, so I added a little lip on the back. the small one needed its center of gravity changed so it didn't tip over so easily. So, it got a slight angle to it. And the bottom trap got a curve to the front so tiny bits could slide up the front of it easier. And the Spider web??? I just like Spiderwebs. I have now also added a version that does not have the spiderwebbing for those that don't want the webbing.