Thank you Michael for the feedback. very nice and simple. Actually what I was looking for is even simpler. And yes a circular disk. Maybe I was not clear enough. The disk should be inside the capsule (sorry;-)). I was thinking that instead of putting the disk whose diameter is equal to the inner diameter of the capsule, is there a routine of smoothing the boundary between the disk edge and the inner wall of the capsule. I hope this is clearer.
