Build a kitchen island by attaching two 30-inch manufactured base cabinets side-by-side and securing them to a 4-inch toe-kick box that you affix to the floor. Add a butcher-block countertop with an overhang on one side to create space for barstools.
Begin the project by assembling the base cabinets according to the manufacturer's directions. Build the box for the toe-kick using four 1x4s so that it has an outside measurement of 21 inches by 54 inches. Set the box in its location and attach it to the floor using L-brackets so the island remains stable.
Set the cabinet on the box so that the overhang is even around the base. Attach the cabinets to the base using screws. Use more screws to attach the two base cabinets to one another. Cut and attach a back panel to the base cabinets. Finish the panel to match the rest of the island.
Place the butcher-block countertop on top of the island base so that it overhangs about 1 1/2 inches on the side of the unit with the doors and 15 inches on the side where you added the back panel. Attach the countertop to the base by adding screws from the base into the top, using small screws that don't penetrate the countertop.