Hi Dan! The stringy hinges are pretty normal with a model like this. The problem is that the hinges are all overhangs - meaning they are printed with nothing below them for support. They need to be this way so that they can move freely. As you are probably aware, there are a huge number of parameters to tweak than can affect how well your printer can handle overhangs. Different filament types will also give very different results. As a result I don't think there's a "magic answer" for how to get the best results with overhangs - it's just a matter of experimentation and experience with your printer and various filaments. Also, since you're using Simplify3D, you can use their excellent custom supports features to generate supports for at least the hinges on the bottom to clean those up a bit. Although I haven't tried it, I suspect that using supports for any of the other hinges would result in a mess that would just fuse the cubes and hinges together. Just my thoughts - happy to hear from others on ways to improve the results.