Install pressure-treated boards for wall framing that will support an L-shaped bar. Design one end of the L-shape to attach directly to the wall framing. Build the bar counter parallel to the wall, with one end open, so you can walk behind the bar.
Cut wall framing soleplate, the top plate and wall studs from 2-by-8-inch boards, using a circular saw. Install the soleplate first, top plate next and studs last to fit the wall on 16-inch centers. Drive 4-inch screws to attach the wall framing to ceiling rafters and floor joists.
Cut and install framing sections of the bar base from 2-by-8 boards, which will be covered with wood veneer sheeting. Build the base to accommodate a countertop, 42 inches high from the floor. Connect the bar base soleplate to floor joists with 4-inch screws to outline the bar footprint. Miter corners and connecting joints to create a smooth underlayment for plywood sheathing.
Route electrical wiring through open wall studs and into the bar framework before covering the wall with drywall. Nail up 5/8-inch drywall sheetings and finish seams with joint tape and drywall compound. Apply the joint compound, allow to dry and sand. Repeat this process three times.
Cut sections of 3/4-inch oak plywood with a fine-toothed saw to cover the bar framing. Nail plywood to fully enclose the bar base for holding a veneer covering. Glue veneer sheets after checking all surfaces of the bar for smoothness. Apply glue and allow to dry to a tacky state before pressing veneer into place. Use an electric sander to trim down any rough edges on the bar plywood before applying the veneer.
Bolt upper wall cabinets into wall studs behind the bar. Use premade cabinets with glass doors for visual appeal. Cover the bar with a 1/4-inch plywood base, and bolt a steel support plate into place for holding a professionally installed granite countertop. Hook up electrical outlets on the bar base.