Though we often use drawings, photos and blueprints in the design process, these tools have limitations in their ability to help visualize the final result. A mock-up of the design can give a better idea of the look and feel of a piece than anything else. A full-size mockup can even be placed in its intended setting to give a realistic preview of the finished piece.
A mock-up may require more work than a drawing, but it needn't be elaborate. Cardboard or artist's foam-board are cheap and easy to work, easily cut with a utility knife and assembled with wood glue. Scrap wood can also be used, if possible even the same species of wood intended for the final product.
The mock-up, like the false facade on a movie set, is not intended for actual use. It can be assembled with hot-melt glue and paper clips; what is important is the proportion of the mockup, and that it accurately represents the proportions and shapes of the actual design.
Once built, the model will immediately make clear where a design's appearance and function fall short of expectations. Flaws that would not show up in a sketch or drawing quickly become apparent. It's a simple matter to attack the mockup with scissors and saw, rebuilding and regluing it until it looks right.
In the case of a design which is symmetrical, a mirror can be used to simplify the model-building: simply build a mockup of half the piece (the piece as if cut in two) and place it against the mirror. The mirror will reflect the other half and give the illusion of the whole piece.
With two scrap mirrors (which the local glass shop can supply, sometimes from their scrap bin) one can build a quarter-section of any design that is symmetrical in two directions, such as a table or plant stand. Then lean the two mirrors against the corners of the room, or prop them up perpendicular to each other. Place the quarter-section in between the two mirrors, and the reflections will create the rest of the design.
To create even more realism, the model can be stained or painted to simulate the final product. Draw details such as hinges, pulls and fittings right onto the mockup with pen, paint, or moveable masking tape wherever you want them to appear.
When you're satisfied with the look of the mockup, record the dimensions and shapes on paper, or simply use the mockup as a guide to building the actual piece.