Determine the size of your bar countertop by measuring the area where it will be installed and the size of the cabinet or base on which it will be sitting. The bar countertop can overhang its base by several inches.
Cut several pine planks to a length several inches longer than the planned finished length of your bar countertop. The combined width of the planks should be several inches wider than the planned width of the countertop.
Flatten the planks on a jointer, and then smooth their surfaces by running them through a planer.
Straighten and flatten the edges of the planks by passing them over the jointer on edge. Check the fence of the jointer before doing this to be sure that it is perfectly perpendicular to the jointer table.
Lay a row of bar clamps on a flat workbench, with the clamps separated about 12 inches. Arrange the pine planks on top of the bar clamps in the positions that you want to glue them together. Stand all of the planks except the last one on their edges.
Spread glue on the edges of the planks, and then lay them back down, and press each plank against the one next to it.
Lay another row of bar clamps on top of the pine planks, so that the planks are sandwiched between the bottom row of clamps and the top row of clamps. Tighten all of the clamps until glue begins to squeeze out from the joints between the planks. Allow the assembly to dry for 24 hours.
Take the bar clamps off the panel. Hand plane the panel to remove any excess glue and give it a smooth, hand-worked finish. Soften all the edges of the bar countertop with sandpaper.
Cover all surfaces of the countertop with several coats of clear polyurethane, using a paintbrush.