How to Build a Backlit Countertop

Have the onyx stone cut to fit the dimensions needed for your kitchen or bathroom. Include holes for the sink and mitered edges for joints. This is not something you should attempt yourself; leave it to the stone dealer for best results.

Measure the onyx and draw the dimensions to scale on craft paper. Verify that the angles of all joints are correct.

Cut the craft paper along the drawn lines, including the hole for the sink. Write the dimensions along each edge of the paper for clarification.

Work with an electrical contractor to determine the best location and wire route for the new electrical box that will house the wires for the LED sheet.

Draw a small-scale version of the room and countertop area on graph paper. Include the location of sinks, joints and the electrical box. Use careful, accurate measurements to ensure the image is drawn exactly to scale.

Send your craft paper pattern, scale drawing and a separate list of measurements to the LED light panel company so they can build a custom panel to your countertop specifications. Play up the natural color of the onyx by choosing a white light panel. You may have the option of bright white or off-white for a warmer glow.

Cut Medex water-resistant MDF board to fit the counter dimensions. Install it as the substrate for the LED panel and onyx countertop. Set the Medex in place and check for level. If the substrate is not level, glue thin strips of 3- to 4-inch-wide Medex to build up the layers to make it level.

Install the electrical box for the LED panel in the designated location. Contract all electrical work out to a licensed electrician to avoid injury.

Set the LED panel in place over the Medex substrate material. You may secure the panel with epoxy resin, but this is unnecessary and makes it difficult to remove the panel if repairs are required.

Connect the LED panel to the electrical box. Route the wiring to the nearest junction box to hook the panels up to electricity. This should be done by the electrician. Turn on the power and test the lights to ensure that they work. Test the light dimmer switch, if applicable.

Set the onyx in place directly over the LED light panel and adjust it to fit against the wall and at the joints. Join the seams of two pieces with two-part epoxy. Sand it with a random orbit sander and 220-grit sandpaper to create a smooth finish.