How to make perfect edge rings in the middle on an object
 

Thats what I wonder. Not common edgerings surrounding an object, But I want to know how to insert some kind of ring on the surface of a polygon. Like if I want to make a perfect hole somewhere, how do I do it ?

one way you could do it (and some will groan) is to do a boolean subtract using a cylinder. afterwards you could delete the history and then delete the faces of the cylinder inside your object. there's your hole.

Thanks a lot! Havent thought of it that way! Will try it right away!

the split polygon tool has some settings you can adjust so that the magnet sticks to your specifications. that might be a way also but the bolleans sounds good.

For some parts of my model (working on the "pod" for the baby on my challenge)

I could use booleans, but on some parts it couldnt be used, on those parts I stuck a Cylinder trough the place I wanted the hole to be (not combined) and then I used the split polygon tool with the cylinder as reference, then deleted the cylinder and deleted the round shape, tweaked some edges etc.