I mounted a VG Racing roll cage for an E-Revo to my MT410 with mounts that I printed, but they're not using the body mount post holes. They're integrated into the shock towers and much stronger. I didn't think that using the body post mounts would be strong enough.
They're shown starting
here in my build thread. I'll probably do a slight redesign at one point or another. I want to be able to easily (or make it easier, anyway) remove the cage along with the lights and camera stuff. It's something of a chore now.
Aside from that, there's nothing that will really take a beating other than that as everything else I printed is a piece to mount something. There isn't anything that's going to directly be subjected to a high level of force.
There are plenty of sites available online that will print parts for a price as I understand it. I've seen discussions on it. I've never used them myself, so I can't really comment on them. There are different filaments (the plastic printed) that can be used. Some will be suited to a more abusive environment more than others.