How do you handle easy head swaps on custom figures?

I've tried that but it just doesn't seem to be very reliable since one slip up with the dremel could ruin the plastic. The only figures I know of that have easily removable heads that still fit tight and move are Star Wars Vintage Collection figures, and I've thought about taking the expensive route of buying a few of them, taking a neck from one of them and planting it onto the chest of a larger custom, and then hollowing out the custom head to fit around the SW figure head so it works like the VC figure. I'm not sure if that would work though.

You can do this by slightly hollowing out the cavity where the neck joint attaches to the head so that it can pop on and off easily, the other more fancy way that I know of is to install a magnet in the head and in the neck so that they attach magnetically to each other.