Hi,

Both Rhino and Blender are great for modeling. Rhino takes some time to get good with but it's a fantastic modeling program for objects that are less organic, like a phone case.

When you open the programs make sure your scale is set up properly. I'd use mm or cm for a phone case. Make sure everything you model is perfectly scaled when you build it. Both have tools for measuring things.

I primarily model in 3DS Max and frequently have things that are out of scale when I import into a slicer. But, most slicers have a "scaling" function. For instance, not matter what I do, my models from Max come into Slic3r at 1/10th the scale I modeled at. So, in Slic3r, I just set the scale to 10 instead of 1 and my prints are perfectly scaled. They are so perfect it amazes me. The other day I needed a cap for a piece of 1.5" PVC pipe. I built it in Max and make the inner diameter 1mm bigger than the pipe. I printed the cap and it fits perfectly. It slides on without getting caught and it does not wobble once one. I'm constantly amazed at the accuracy of my prints.

So, it all comes down to either setup or scaling later in the slicer. As long as you model accurately to start with, the final print can be scaled to be exactly what you need.

For instance, I needed a charging base for my new iPhone. So I designed one and printed it. I built it in Max, pulled it into Slic3r and scaled it up 10x and printed it. It fit the phone perfectly. I always leave .5mm clearance and so far that has worked very well for everything. Blender or Rhino could have built this just as well. In fact, I started it in Rhino but then went to Max because it's such a simple shape.

iPhoneChargeBase.jpg