It wasn't too long ago I made the Dr. Frankendollfie post. This is a follow-up.
I wasn't quite satisfied with the part where the spine connected to the hip.
The problem? The upper body could spin easily but overall felt too loose. With the first one I built, the spine didn't dislodge from the brass pipe piece so I left it alone. As of this writing, I made 3 of these things and one of them dislodged. Since I wasn't satisfied with how the pieces felt loose, I'll eventually modify all 3 but for now, I did the following modification with only one of them.
Originally, there was only one screw and one nut holding the brass pipe to the hip piece and while the spine didn't dislodge easily for 2 of the 3, they were all loose. I drilled a another hole through the brass pipe and also drilled through the spine. I also added an additional nut to the first screw just because I thought that provided a more symmetrical look. While I don't know if that did anything extra from a functional standpoint, the connection between the spine and hip is very solid now.