[gene-h]

The big problem with stereolithography resins is that they tend to degrade with time, especially if left in the sun. Photocuring is carried out by creating free radicals to induce polymerization. Well it turns out that these same free radical producing chemicals stick around even after the curings done and can make more free radicals if left in light. These free radicals can cause some pretty nasty damage to polymer chains. The chemistry is improving though, at the very least to allow more interesting materials like silicones. One can mix in composites to stereolithography resins, but in general this isn't done. The problem is that whatever you mix in scatters light, so light doesn't penetrate as deep, so curing takes longer. Unless the composite used is transparent and has the same index of refraction as the resin, it would not be possible to use this tomographic approach to make parts.

There is one application of composites that's extremely disruptive though: producing ceramic parts. It has been found that you can mix in ceramic powder with the resin fire it in an oven to make very detailed ceramic parts[0]. Structural properties aren't necessarily that good, but that's ok because it's good enough to make very complex and detailed investment casting molds[1]. Investment casting molds for making single crystalline jet turbine blades are very complex and require a very complicated process to produce, with this process they can be made in one step. That's a huge disruption right there and investment casting is a pretty general process. The detail produced by this process is so high that the the triangulation of STL became a problem and a special file format developed for fax machines had to be used to represent all the slices.

[0]https://www.researchgate.net/publication/229293237_Photopoly... [1]http://ddm.me.gatech.edu/page8/page8.html