The WSM cooks better when the charcoal ring is at least moderately full.although the fire will go out eventually it wastes a lotoffuel for short cooks like ribs. I made a smaller diameter ring to allow you to fill to a good depth with less fuel for short cooks.
Light guage expanded metal, tin snips, bailing wire & a measuring tape , works great , very inexpensive, easy to make (4 in height)