The present invention provides a method for manufacturing a walk-in bathtub. The method involves heating an acrylic sheet, wherein the outer perimeter of the sheet is heated to a higher temperature than the center of the sheet. The heated acrylic sheet is then placed over a vacuum mold that is shaped like a bathtub, including a seat and a foot well, and drawn into the mold by the vacuum. Vacuum pressure is manually reduced when the acrylic reaches the top of the seat in the mold, and the vacuum is shut off when the acrylic is approximately two inches from the bottom of the foot well of the mold. The acrylic is removed from the mold, reinforced with fiberglass and secured to a support frame. A door space is cut in the side of the tub and a pre-hung door assembly is then installed in the door threshold.