Re: cutting a "heart" into a "common chamber"?
In a common chamber that is plated, the chamber is a big hollow heart, no tubes, no anything, hose ports draw straight from the smoke inside the heart. There is a solid plate covering the chamber so you cannot see inside it, or clean it well. these holes don't lead directly to hose ports or purge valves.
A common chamber that isn't plated is just that.
A traditional chamber does not have a hollow heart in which smoke sits. The smoke is drawn directly from the base, not the heart, through a tube leading DIRECTLY to the hose port. The hose ports DON'T draw from a hollow center heart.