Alon Toker says most manufacturers offer trim kits to give microwaves a built-in look. Designers can use the kits or spec custom molding to match the cabinetry. Toker says trim kits give the appliance an industrial look. For his clients who prefer a softer look, both stock and custom cabinet companies offer wood trim to match their products.

When Christopher Repp is installing microwaves, he makes sure to leave 2 to 3 inches around the back and sides of the unit so it can breathe even when the front face is trimmed. But he suggests checking the installation instructions for manufacturer guidelines on space requirements.

Glen Doyle says some manufacturers include air intake grills in the kit to help circulate air around the unit. In Toker's experience, a 1/16-inch clearance is adequate because the appliances generate very little heat.

Many designers find it challenging to fit a microwave into stock cabinets. Repp has a cabinet shop, so he can quickly make or modify stock cabinets to fit the microwave. "We don't have to worry about tight tolerances or bring in the unit to make sure it fits," he says.