A bookshelf must be constructed using strong wood. If you're looking for a cheaper wood option, go with Grade A or B plywood sheets. Avoid medium-density fiberboards (MDF) or particle boards, as they tend crumble easily under pressure. Cut the bookshelf panels for the frame by using the desired height, depth and width measurements; the side panels must measure height by depth, while top, bottom and shelving pieces must measure depth by width minus the thickness of the wood to make room for the side panels.
Assemble the bookshelf frame. Place the top piece on its side, and do the same for the two side panels. Place the top piece between the side pieces, so you create a U-shaped wooden frame in which the side panels overlap the top piece. Connect these corners using screws and a cordless screwdriver. The screws must be longer than the thickness of the side panels to ensure the pieces connect properly and securely. Insert all desired shelves between the two side panels and attach in the same manner as the top piece. When done, screw the bottom piece in place between the two side pieces so you have a rectangular frame with shelving.
A common bookshelf has a back panel that ensures that the books and other items and decorations don't fall out the back side. The back panel should be created using the same wood type as the frame, and it must measure the total height by the total width of the unit. Attach it to the frame using a hammer and nails, placing the nails around the back panel's perimeter. The nails must be longer than the thickness of the wood. The front of the bookshelf can be left open or be covered with a door, which would be identical in size to the back panel. This door is attached with hinges and can be made of wood to hide items, or of glass to offer a view inside. The hinge screws must not be longer than the wood's thickness.
Bookshelves can be primed if you desire, to keep the wood's natural color. Stain the bookshelf if you want to darken or color the wood slightly. Other options include painting the entire bookshelf for a bold look. Add several coats of paint for increased brightness.