In woodworking, there’s a sound, logical sequence of steps you need to take from start to finish. It’s the same in SketchUp, so work in SketchUp the way you would in the shop: define the steps and sequence you need before you begin modeling.
Suppose, for example, that you’re designing kitchen cabinets. The best way to do that is to begin with the cabinet sides. They’re the main structural element, holding the other parts in place. Draw one side to size and add rabbets and dadoes for the bottom, back, fixed shelves, and toe-kick space. Copy the side and do a Flip Along command to mirror it (this orients the copy correctly, without creating redundant geometry). Fill in the fixed shelves, the bottom, the back panel, and ledger strips. Next, attach a face frame. After that, position whatever drawers, doors, and adjustable shelves you want. Finish by adding knobs, pulls, and other hardware. Those are the steps and sequence you’d use to build the project, so that’s the way you should model it.
You can follow pretty much the same sequence for any case piece—essentially a box with shelves inside and a door on the front.
With a more complex piece, such as a dresser or a sideboard, constructing the SketchUp model as you would the real thing allows you to preview the glue-up. By using SketchUp’s X-ray mode, you can peer into components to see if tenons clash with others, if dowel holes align in mating parts, and so on. It’s a sort of a dry fit for the dry fit.
In the shop, you begin a project by milling all the wood square and to its final width and thickness. With that done, you go on to cut pieces to length, adding the joinery and dry-fitting the pieces.
You can work the same way in SketchUp, although it’s not a good idea to make all the components at once. It’s better to add components in place so they fit precisely against mating pieces; that ensures that each new piece will be the exact size you need.
To take a simple example, suppose you’re making a small occasional table with tapered legs, connected to stretchers with mortise-and-tenon joints. The first thing to do is define the first step in your modeling sequence.
As you would build a table, begin with the legs. Start with one table leg without a taper or mortises. Copy that leg component, and do Flip Along commands to position all the legs so that each leg component has the appropriate orientation. That’s easiest to do when they are square. Open one leg component for editing and create the taper.
The next step in the sequence is to make the stretcher. Draw one in place between two adjacent legs. Give it thickness and make it a component. If the table is rectangular, repeat for the second pair of stretchers. Copy the stretcher components and position them between the legs: a rotational array works well here. Add tenons to the ends of the stretchers to set yourself up for the next step in the modeling sequence.
Now, similar to how you would in the shop, use the tenons to size the mortises (in the shop, it’s better to make a mortise first and size the tenon to fit). Open one leg component for editing and zoom in for a close-up view of the top area, where the stretcher touches. Switch to X-ray mode so you can see the tenon even though it’s buried in the leg. Trace over the base of the tenon with the Line or Rectangle tools. This produces a tenon-sized area on the leg. Use the Push/Pull tool to push that area to the end of the tenon. Orbit around and repeat for the second mortise.
That completes the table’s structure. Now you’re ready to attach the top. Use the Rectangle tool to draw a rectangle in place right over the top of the legs. With the Offset tool, enlarge the rectangle for the overhang you want. Erase the original rectangle, give the top its thickness, and make it a component.
Working in SketchUp as you do in the shop is my final rule for success*. Above all, always work with components (that’s Rule #1). Draw a piece once and make as many copies as you need (Rule #2, which ensures accuracy and makes the SketchUp work go quickly). And keep the measuring and moving to a minimum (Rule #3, which also ensures accuracy).
*Ed note: You can read more of David’s "rules for success" in his book “SketchUp Success for Woodworkers: Four Simple Rules to Create 3D Drawings Quickly and Accurately.”