1 I found a comment that the original version of the second stage was busted, and they released an update.

I've run into a lot of non-manifold models. Some of them auto-repair easily enough, some remain unprintable even after running them through meshmixer or meshlab. Others seem to be orientation-dependent, and tinkering with the rotation will let the auto-repair work.

-j

2 Just for fun, I downloaded the updated stage 2 model, rotated the pieces upright, and sliced it with 5% adaptive cubic infill. It predicts a print time of just under 24 hours with 333 grams of filament.

-j

3 My prints came out okay, but I wasn't able to split them exactly on the seam I wanted to. It's hard to get a good look at the interface between the model and the build plate. And the rotation in 1 degree increments failed to land it perfectly flat. (Align face to build plane also failed.) But I have a benchtop Belt Sander, so I can make those problems go away.

Tomorrow I get a "3D Pen" which I hope I can use to cram filament into the seams.

And wow, my print looks a LOT better than the sample pictures! (But the slight angle meant that the nozzles, which I printed facing up, had slightly detached bottoms on two of them.)

Next stage is printing. Then I think all I have left is a connecting ring for Stage 1-2. But there's no LEM.

4 Cura has a Snap Rotation checkbox, and also a Lay Flat button that adjusts the current rotation so the nearest flat surface is level with the bed. The one thing to note with that is that it might not drop it to the bed automatically after fixing the orientation.

Which 3D pen did you go with? The Mynt3d Pro has decent reviews and replaceable nozzles, so it's on my list as a "maybe" for connections, repairs, and using up the last few feet of filament from a spool.

-j

5 Apparently because of the Not Manifold errors in the stl for the second stage, I couldn't make things align. I got my hands on a copy of MeshMixer from autodesk, but I don't know what I'm doing with it. Although the analyzer showed all kinds of errors because so many of the surface features apparently were never booleaned with the body of the shape, and they have protrusions into the interior of the model.
I got a Scrib3D pen. It worked, after a fashion. Not a problem with the pen, but the gap I was filling was pretty tight, so I ended up with a lot of overflow that needed sanding off. I don't know if I'd ever use it for its INTENDED purpose. The ceramic tip was also hot enough that it did a little work on the print I was fixing itself. It definitely requires practice.

6 Meshmixer and Meshlab are both extremely powerful applications with basically impenetrable interfaces. I pretty much Google for what I want to do with them until I find a tutorial. :-)

-j

7 I'm going to give the resultant print (over 3' tall!) to Sarah.