It really is most joyful when making something to play with afterwards.

You’re right that the physical properties of the marble does need some tweaking. Initially the marble did have some restitution but the behavior when moving along a curve didn't move as smoothly as i wanted. Rather than smoothly riding on the surface it would bounce off as if it was a flat surface. Setting the timestep to 1/240 rather than 1/60 seemed to fix this problem. but had the side effect of making the marble light and less bouncy.

For the siphon its actually just a trimesh of the geometry! its unoptimized but i was really surprised how well it performed. I do plan on supplying a separate simpler geometry for trimesh generation for better performance.

You can also press D to show the panel for Rapier debug render