Following product instructions, pour dry cement into plastic takeaway container to halfway. Using a water jug, add a small amount of water to cement powder. Mix with stirrer and keep adding small amounts of water to create a toothpaste-like consistency.
Press ice-cream cup into cement mix, centred to circumference of plastic container, until cement is level with top of container. Hold assembly in your hands and gently tap it on the counter top to release any bubbles. Leave to dry overnight.
Holding two sides of ice-cream cup, carefully remove it from assembly. Set cup aside. Turn plastic container upside down in your hand. The cement cast should slide out easily. If not, tap it gently on an old towel on your counter to release it.
Gently sand top ring of cast with fine-grit sandpaper wrapped around sanding block. Then sand a flat area, about 1cm in width, from top to bottom of outside of cast, to stop it rolling when completed. Set cast aside.
Place ice-cream cup upside down on balsa wood. Trace around rim of cup with pencil, making a perfect circle.
Use utility knife to carefully cut out circle marked on balsa. Hold knife at an angle to make cut tapered at back for a neat and tight fit in cast. Check against cast for fit and adjust if required. Lightly sand cut edges.
Make a mark for a centred hole on circle of balsa wood. To do this, trace the circle of balsa onto a scrap of paper. Cut out the circle of paper with scissors. Fold paper circle in half, then half again so that creases indicate centre point. Unfold, then pierce centre of paper circle with your pencil. Place paper circle over balsa wood circle and mark centre.
Drill hole in balsa at centre mark to fit shaft of clock mechanism (ours was 7.5mm diameter). Place balsa circle over shaft of clock mechanism so motor is at the back. Following product instructions, thread washer on core of mechanism.
Carefully attach hands to face of clock.
Insert battery into back of clock (ours required AA).
Carefully push clock into cast for a firm fit.