Inspired by amazing 3D Dynamic Machine challenge by pwnisher/Clint Jones, I started making a marble run.

Just starting off with a simple bit of track to test settings.

  1. Bezier curve - extruding to make a nice simple shape.
  2. Add 2 narrow cylinders and join them together to form one object.
  3. Apply Array and Curve modifier to follow curve
  4. Convert to mesh
  5. Add rigid body to "track"
  6. Add UV sphere and add rigid body
  7. Play to see how it runs.

Main things i've been tweaking are:

  1. Tilt of bezier to make sure ball doesnt fall off.
  2. Friction of both ball and track
  3. Sensitivity margin of both ball and track.

However, i have basically made the friction and sensitivity about as low as possible but the run never seems that smooth. It seems to get caught up for no particular reason. if settings are too low, the ball seems to "twitch" a little.

Obviously hard for anyone tell me exact settings needed but any advice on how to proceed with tweaking would be gratefully received. Or just confirmation that it really does take loads and loads of iterations to get the right settings!

Thanks Richard

enter image description here

  • $\begingroup$ please provide blend file $\endgroup$
    – Chris
    Aug 17, 2021 at 13:15
  • $\begingroup$ <img src="https://blend-exchange.com/embedImage.png?bid=3ymZZR6A" /> $\endgroup$ Aug 17, 2021 at 14:18
  • $\begingroup$ so it isn't as bad as i thought, but there's still a little weird bit at the middle of the track. still interested though in peoples thoughts on how to design the track etc. $\endgroup$ Aug 17, 2021 at 14:20
  • $\begingroup$ when i give a solidify modifier on your track, i got this: [1]: i.sstatic.net/zI9EX.png. So i think you did something wrong with your cylinders and array modifier. $\endgroup$
    – Chris
    Aug 17, 2021 at 14:44

1 Answer 1


Honestly, i am not sure why the weird movement is in your setup. I assume double vertices - but i am not sure.

But...i have a setup which works:

  1. build a beziercurve

  2. double it and move it (so you have 2 tracks)

2b) convert to mesh

  1. at end or start connect the last vertices with "F"

  2. add skin modifier -> check smooth

  3. Tab -> edit mode -> A -> select all vertices -> then CTRL-A -> S -> scale down until it looks good -> apply modifier

  4. add rigid bodies to track + ball


enter image description here

  • $\begingroup$ nice. thanks. although if you put a bank in the track you'd have to tilt both beziers? $\endgroup$ Aug 17, 2021 at 19:18
  • $\begingroup$ i didn't tilt the beziers, i just moved the vertices on xz - plane ;) $\endgroup$
    – Chris
    Aug 17, 2021 at 19:38

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