Here is a concrete clock made from tupperware, a funnel, and a piece of foam.
The form is pretty easy to make and uses a standard clock mechanism that you’ll find in most any craft store in the usa.
This project was completed at work and the point was to find cheap forming materials that make it possible to cast a unique clock out of concrete. Although a lot of sketches were made, the final form was dictated by the plastic tupperware container and the plastic funnel.
The interior form (blue) is attached to the exterior form (orange) with silicone. Then a foam knockout (light blue) is pressed onto the spout of the funnel to create a void to recess the clock mechanism.
The knockout for the clock mechanism has a hole drilled in it and slides onto the funnel. It’s stuck in place with silicone so it doesn’t float up during casting.
The form is filled with concrete and vibrated to eliminate voids in the concrete. This is a 5000 psi. concrete mix that is pigmented purple.
After the piece has cured, the form is removed and the funnel is pulled out of the concrete. Then the face and back of the piece are polished flat.
The blue funnel is removed, leaving lines at 12, 3, 6 and 9 o’clock.
The foam knockout is removed by prying it out with a flat screwdriver. Then the face and back side of the piece are polished, which exposes the aggregate in the mix.
Two holes are drilled in the concrete and stainless rods are glued in place so the clock sits up off the table. The clock arms are bent to clear the funnel shape, and a piece of cork can be glued to the back side to hide the clock mechanism.
