Alrighty then, I had a peek at your cool gothy necklace
First of all , in Max, the piece appears too small for a necklace at 8-9 centimeters long. This might be big enough for a delicate bracelet in a perfect world. Unfortunately, at this size, the rings are pretty small to be printed with any confidence for the imperfect world in which we live
. At best, the wire size of the rings should be 2mm in diameter. At worst, they shouldn't be any smaller than 1mm in diameter. As it is, they are not quite .5 mm, which is very thin. This might be a scaling issue in the program, so I resized it up 200% so that the rings would be at least 1mm which for me, is still to small for these rings. This makes the necklace about 17 centimeters tall (6 3/4 inches).
So, secondly , I think the diameter of the rings should be bigger. At 1mm, they will be flexible in the SWF material, and in any other material they may break. Since a necklace has so many rings, it is inevitable that one or two rings may not make it in printing using the detail materials - perhaps more in shipping. On the safe side, I would aim for at least 1.5mm in diameter.
Also, the rings that are part of the wings that attach to other rings below, are a little odd, because I think they were sculpted as part of the wing. Because they are odd, I don't think they are structurally sound, and will easily break. Instead, I would resculpt the wing without the rings. Then I would embed a torus in the bottom to match the other rings of the necklace, as you have done at the top of the ring.
Next , I think you should use boolean functions to attach the horns and side rings to the head. I did this in max, followed by using the "cap holes" function to make the head watertight. This will stop you from having any manifold issues, because you won't have separate elements overlapping.
And finally , you might want to rethink your ring-design in terms of how the necklace lays on the body when gravity is introduced. At the moment, gravity will make the wings cross each other and jumble up behind the head. So I would recommend you take the rings off of the top wing tips, and place them somewhere around the horny bits on top of the wings.
Unfortunately, designing for 3d printing takes a bit more work because of the manifold issues. You will probably have to alter your approach to design compared to the good work I know you do in other platforms. Test out other 3d programs. Use different processes that aren't prone to making holes or manifold edges. This will take some time, but it's worth it.
If you were starting this necklack from scratch, I would tell you to sculpt the head and the wings in your program of choice, without the rings. Then do some tests to make sure they are watertight and manifold. When you have achieved this, I would then import them into max, or another program where you would make the short tubes, or tori that create the rings for the necklace.
Hope this helps!
-Whystler