Cut your table base. Set three beer kegs tight together in a circle on top of the plywood. Draw a circle around the bottom of the kegs on the wood. Using your skill saw, cut out this circle. Sand any rough edges if needed.
Screw the plywood circle into the kegs to hold them securely together and in place. Turn the structure over and this bottom "plate" of wood will keep the base level and keep your table from tipping over on even the roughest decks or porches.
Spray paint the whole table, including the kegs, in your choice of color, using an outdoor metal spray paint.
Have a thick piece of table glass cut for the table top. You can fill the top of the kegs with personal items, such as a bottle cap collection, or trip mementos, such as matchbooks, before placing the glass on top.
Spray paint four beer kegs to match the table.
Cut round pieces of thick cushion foam that fit securely in the top of the kegs.
Upholster this foam with your choice of outdoor all-weather material, which can be found at any fabric store; just ask for material that is meant to be used outside. Upholstering can be done by sewing, stapling the bottom side, or by simply using liquid seam glue. (All of the supplies for any of these methods can also be found at the fabric or craft store.)
Place one finished seat cushion in the top of every keg. Before pulling them up to the table, have a seat and admire your brand new table and chairs made from beer kegs.