Scale any part independently along X (width), Y (height / stack axis) and Z (depth)
in the VAB/SPH. Only the physical model (meshes + colliders) and attach nodes are
changed - mass, cost, resources, thrust etc. are NOT affected.

TweakScale / TweakScale Rescaled (optional): the stretch is applied on top of
TweakScale's uniform size (final size = TweakScale factor x stretch per axis).
Changing either one keeps the other. Mass/cost scaling still comes only from
TweakScale's uniform factor.
