Design a 5-shelf unit approximately 200cm tall × 80cm wide × 30cm deep. Cut the two side panels (200×30cm), five shelves (80×30cm), a top panel, and a back panel from 18mm plywood or pine boards. Label each piece.
On both side panels, mark the height of each shelf with a pencil and square. Standard spacing: 30cm from the bottom, then every 35cm. Use a spirit level to ensure marks are level on both sides.
Using a pocket hole jig set to 18mm thickness, drill two pocket holes at each end of every shelf board. These create strong, hidden joints.
Stand the two side panels on edge and clamp them. Attach each shelf using the pocket holes and screws, checking for square at each step with a framing square. Work from the bottom shelf upward.
Lay the unit face-down. Cut a 6mm plywood back panel to fit. Nail or staple it to the back edges of the sides and shelves, squaring up the unit as you go.
Sand all surfaces starting with 80-grit, progressing to 120, then 220. Apply two coats of your chosen finish (stain + polyurethane, or paint), sanding lightly with 320-grit between coats.