The above post is correct splines when used for any purpose must have no rotation on the 'Y' axis, otherwise problems like yours will occur. This problem is highlighted in the spline tutorials on this site. From the Splines The spline can now be given any name as long as it includes the name ' spline ' in any part of it i.e. road1_Spline or roadspline01 etc. Problems will occur if the spline transform or the spline itself does not have the correct rotation, whether in the transform group of the spline or the spline itself . The rotation has to be set at 0,0,0 for any of the scripts to work correctly. There are a couple of ways of ensuring this, one is to set up your spline in the position you want and freeze transform only the rotation, the other is to select the S cv of the spline and delete it, this brings S to the centre (rotating point) of the spline, then just use the E cv to create the rest of the spline so lessening the chance of inadvertently rotating the start of the spline.

Das musst Du machen

@WrinkleysRule I'm hoping this is something I'm doing wrong, but I can only get the splines to paint correctly in one direction. I just downloaded the file that's attached to your first post in this thread, Dec, 2024, which is the only one I could find--hope it's the correct one. The below pic is a sample of four identical splines where the Y axis is rotates at: (from left to right) 0, 90, 180, 270 (-90). Any help on this would be greatly appreciated! Thanks!

You’re welcome hope they’re working well.

Thank you for this update!