Spline IK to rigify rig

I have a rigidified character with some extra bones like a tail. I have been trying to find a way to add a spline IK to the bones, but in order to add a spline I must do it in object mode. When I add it in this mode, I cannot access it when I am in Edit mode on the rigify rig. I cannot create the spline in edit mode. I have searched for tutorials, but I have not found anyone who adds a spline IK to the rigify rig. How is this done?

Also, I want to add a spring to this tail, but there is no spring constraint. I saw this in another video, is there an add-on for the spring constraint? If so, where do I find it? Thanks in advance.


Sorry for bringing up this old thread, but I’ve the same question.
I am about to finalize the meta-rig for my anthro dragon. I did some pilot testing and everything seems to work fine, the only thing I need your help or recommendation is the preferred way to rig his six ‘dreadlocks’ (basically tentacles) which are next to his head AND make it work with the rest of the final rigify armature. I wanted to try out a Spline IK like shown here, but before doing that, would it even work? Or is there even a more elegant solution?

In the optimal scenario, the tentacles (being passive props which I don’t want to animate by hand every time) shall work by mere gravity, aka move with the movements of his parented head and correctly collide/touch with the rest of his body, rather than intersecting like visible on the right. If you guys have an idea for that as well, I’m all ears :upside_down_face: Thanks

Edit: I started learning blender about 1.5y ago and this is my first project^^