Hello everyone...
The HawgFather here. I have been following this thread for quite a long time and enjoy reading and seeing everyones ideas. I just joined the forum. Now on my 16th UDS. Trying to make them cheaper and cheaper because everytime someone tastes the Q from my UDS, they want one of their own, which I end up helping them build. Concerning the bottom vents here is a pic of a sliding door from a cheap donor grill that works great. You can see my take on the UDS here and the last one that we built at the bottom of page (Under $100)
http://hawgfathers.com/RD.aspx