So, I have a niche question, one I can't find a single resource on the internet for. I'd like to know how I can create a cylindrical-looking light beam line that can be manipulated along a spline. Examples of this in games can be seen in the mobile game Smash Hit:

And in Super Mario Galaxy:

As for technical details, I've been looking at Mario Galaxy's launch star trails. It looks like the launch stars are made of textured cross-planes, as we can see from this camera angle:

How could I create something similar in Godot? Ideally, it'd be something that I can do in the editor.

And, I've already tried the CSG Polygon node. That's an excellent solution... if it worked. In order to create a cross shape like shown above, I'd have to create many overlapping vertices and the UVs would be non-editable, making that solution invalid. I wish that node allowed using a custom mesh instead of having to input the coords of vertices.

Is there any particular reason you're relying on a spline? Why not use a particle trail? Or are you needing this trail shape to be a working mesh with a collider?

    Lethn No colliders, it just never occurred to me that particle trails would work. I always thought they were for dynamic purposes and not static objects. The purpose of the spline is being able to create a path that has the glow on it.

      Well you'd have to kind of fake them being static, but I'm fairly certain it's possible, remove gravity and give them a lifetime of 0 etc. plus you'd have to put in a trail sprite that works, you'd just need to experiment to get the result you want.

      Here's what it would look like in Blender:

      I used an array modifier with the fit type set to Curve and I created a Curve modifier to deform the mech along the curve. Is there a way to do the same in Godot?