Here's How

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  Step 1: With door on workbench, mark centre point along width of door. Add half the thickness of door (here, 23mm) to 1 side of centre and mark a new point. Draw a line along whole length of door through this point.
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  Step 2: Prop door on timber offcuts close to midpoint, leaving a gap underneath line to cut along. Clamp a straightedge along marked line, holding door and offcuts in position so door doesn’t drop when you finish your cut. Set your saw to cut depth of door and make a cut hard against straightedge.
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  Step 3: Wearing dust mask, lightly sand all door surfaces with power sander.
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  Step 4: Predrill an even spread of pilot holes along cut edge of wider piece of door. These holes should be made in thicker parts of door and close to edge (no further than thickness of door).
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  Step 5: Apply PVA to cut edge of thinner piece of door, then hold up wider piece at right angle. Check for square, then predrill through pilot holes into adjoining part of door. Drive a timber screw through each hole to secure components together.
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  Step 6: To make shelves, you need to cut a quarter circle for each shelf. Measure depth of desired shelf from join of doors, out. Mark measurement on a timber offcut and drive a nail through offcut at this point. Place point of nail in a right-angle corner of plywood sheet and, using nail as a pivot, mark curve, from edge to edge.
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  Step 7: Cut out each shelf along marked curve with a jigsaw and lightly sand edges.
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  Step 8: Mark position of shelves then predrill an even spread of pilot holes. Apply glue to edges of shelves and hold in position. Drive screws through each pilot hole to secure shelves.
• Step 9: Undercoat all surfaces in Dulux Preplock. Allow to dry. Lightly sand surfaces.
• Step 10: Finish with 2 coats of Aquanamel. Allow to dry. When door shelving unit is in place in your home, secure to wall at top with fastenings to suit your wall type.