Roadstone is a script for 3d max a generator of a stone track. It is well suited for exterior projects. You just need to create any closed spline select it and drag the script into the scene. The script comes in two versions for a river stone and slate stone track. Materials textures in 4K resolution of stones and a scene are also included. In order for the script to work correctly the units of measurement of your scene must be in centimeters/meters. It works in versions 3Ds Max 2018+ inclusive.

You can find out all the details about the work in the blog:
https://3dsky.org/blog/post/road_stone_3ds_max_script 

I also suggest watching a short video tutorial on using the script:
https://www.youtube.com/watch?v=i4nJgWRBgb4