How can I create a zero-mass object?

When I create a Rigid Body in BGE, it won’t allow me to lower the weight mass to complete zero 0. And no I can’t use ex. No Collision because the Logic Brick “motion” servo motion cannot move their x/y/z location if I do that. Their motion must be "physics so they are recorded by BGE’s “Record Animation” button.

I’m trying to make a bunch of dummy objects move with my baby’s face, which will have force move their location/rotation, and have a location/rotation limit. They must sit in the middle of their limit. Problem is I could make rigid body joints or “hinges” BUT their weight will make them fall to the bottom of their Z limit making all the face droop/hang. :frowning:

Their motion must be "physics so they are recorded by BGE’s “Record Animation” button.

Since years now, you are no more forced to use BGE to record rigid body animation.
And for rigid body simulation outside of BGE, you can disable effect of gravity for the RB world.

What you want to achieve is not really clear for me. But I doubt that a rigid body simulation will help.
Can you provide a video example of what you want ?
For a rig, maybe there is a more efficient way to create delays simply by bone constraints.

I’m simulating a baby intelligence and so I need BGE, then will render a HD movie in Cycles by recording in BGE by that button. Therefore shutting gravity down globally won’t work (unless I do this on some runs lol!, but no).

More importantly I realized last night I’ll need the face bones (well, controlling Rigid Body objects) to spring back to where they belong, else face droops/hangs. That may actually cover-up gravity pulling them down (besides a lil gravity is natural!). Therefore I will create a new thread about “spring physics for a face”.

Update: just what I needed

http://bulletphysics.org/Bullet/phpBB3/download/file.php?id=640&sid=7c2ee2d4233a200a7069367c52979f40

If you’re up for seeing it yourself in action, all I did was add 3 bricks below there’s (of the top cube) that makes it move ex. left when you press A. I used Simple Motion. And was able to record it into Cycles. Looks good.