I found that the head in the "Braq" Jointed Dragon had way too many manifold errors for slic3r 1.2.6 to handle.
I've since added all of the other parts.
I've printed these myself on my RepRap - a modified version of RepRapPro's Ormerod 2
I've repaired the mesh so that slic3r can use it. For directions about assembly see the original
I used Netfabb cloud to fix the original STL
Info about netfabb cloud:
BQ labs thinks they may have fixed the issues with the original head. However, I'll keep this item available, as other parts had issues as well, and I haven't confirmed that the head is actually fixed.