If I build the arm from separate objects is there still a way to skin the joints? The skin at the forearm and elbow needs to stretch as the joints move (I've gotten a nice looking stretching skin arm to work using bone animation in MED).

The arm itself does not need to be a physics object as we will be controlling its physics externally (This IS necessary as we have a complex model involving dozens of muscle segments and other nonlinear components that is already implemented externally to calculate the joint angles).
Objects that the arm/hand will manipulate should be physics objects. Unfortunately, this conflicts with what the 3dgs manual says: "Non-physics objects must not collide with physics objects, but physics objects can collide with non-physics objects". For example I would like to have the virtual arm pick up a cup. If the person controling the arm causes the arm to hit the cup too fast, the cup should fall over or scoot across the table with specified friction, gravity, etc. (Equal and opposite forces would then be sent back to the external "dynamic arm model" that controls the joint angles of the arm.)

Questions:
(1) Is there a way around the "Non-physics objects must not collide with physics objects" issue?
(2) If the arm does need to be a physics object to avoid this issue, is there a way to prevent the collision results to be displayed and rather send the information to our external model?
(3) Can you have non-physics objects collide with physics objects in Newton?
(where can I get Newton, and information on how to use Newton with A6 engine)

Thanks again for the responses