[ODE] Ball should fall through the board (dBox) in some place. How to implement?

[Dmitry Medvedev]

  Hello, everybody.

 I have a long board, made from dBox and a couple of marble balls with big inertia, which are moving around the board. It has some holes to trap the balls and balls should fall through the hole in the board. I see two ways to implement this.

 1) Use mesh for a board with predefine dholes - undesirable variant, because holes should be placed randomly,
 2) Turn off ball-board collision via collide bits, but collidable bits and categories produce error if try to set them during the simulation process.

 Any ideas are welcome.

 Thank you.