A simple way to turn venerable drawing rooms into apartments

As more old mansions are refitted as condominiums, numerous proud drawing rooms are being transformed into one-room apartments. It isn't always easy to make these spacious, often gracious rooms adapt to the new role.

David Eugene Bell and Donald Cotter, principals of Design Multiples in New York, solve the problem in a relatively inexpensive way with a series of movable modules made of Novoply industrial particleboard panels. The flexible modules divide the single room into sleeping, entertainment, and eating areas and can be rearranged as needs change.

One room in an English-type manor house in Connecticut gave the designers a particular challenge. It was 18 feet wide and 27 feet long, with a copper ceiling, fireplace, two bay windows, and wood-paneled walls.

To give the room a focal point, the partners devised a T-shaped modular divider, made of particleboard by a local craftsman. The top of the T is 10 feet long and the stem is 8 feet. The unit is 56 inches high and 14 inches deep. ''It accomplished our purpose of scaling down this very large room and of dividing it into several areas,'' Mr. Cotter explains.

Some of the modules are open shelving for display of art objects and books. Some have storage inside, behind drop-leaf doors. The top of the unit conceals lighting beneath egg-crate baffles. A regular twin-size boxspring and mattress is arranged on either side of the stem of the T, providing two sofa beds which can be used for both sleeping and, with the help of plenty of plump pillows, seating.

The entire unit is painted a color called ''wet sand,'' which blends with other tans and beiges used in the room. Some black lacquered furniture and the accent provided by daffodil yellow upholstery on two French chairs complete the color scheme in the conversational grouping.

Other furnishings in the refashioned room were the small round table in front of one of the sofas, end tables, and lighting pedestals. All were made from particleboard. The two bay windows were fitted with fold-down shelves, at sill height, which could be opened to provide table surfaces for tea or dining or study.

Dimensions of the pieces could be adjusted to suit the proportions of any room. These, or similar pieces, are so simple that they could be made by many do-it-yourselfers.