I’m new to Cinema 4D myself, but I think you can set keyframes for the “Visible in Renderer” command in the Attribute Manager > Basic tab. I’m not sure if that’s the effect you’re going for or not or if that’s even the best way, but just an idea.
The alpha channel worked great. Now the client wants to give the spline a 3D look–right now it’s only 2D with the spline and extrude nurbs. Is there an easy way to add a slight z-dimension to it?
It worked until I tried to move the target layers in z-space–the expression no longer keeps the corner pin to the target layer. I tried different values in the z property to no avail.