How to Build a Box

Enlarge Image Image Gallery You can build a handsome bookcase as well as kitchen cabinets, window boxes and more if you know how to build a box. ILLUSTRATION: LEN CHURCHILL

Boxes form the heart of many types of furniture, cabinets and shelves, bins, storage crates, raised garden beds, and even buildings and large timber frames. After you’ve mastered the basics of how to build a box, you’ll be ready to successfully tackle many DIY projects, large and small.

I’ve been making wooden boxes of one sort or another since getting serious about woodworking in the early 1980s, and the three basic approaches outlined here are the most useful I’ve found. They work well for solid timbers, boards, plywood, particleboard, medium-density fiberboard (MDF), melamine and any other sheet material.

Guaranteed Square

When you build a box, you must make perfect 90-degree corners, and a tape measure is the best tool to use. The trick to knowing you have it right has to do with geometry. When opposite sides of a box are equal in length, and measurements taken across diagonally opposite corners are equal, then the corners form 90-degree angles, and are “square.” You can bet your life on it. (See the illustration in the Image Gallery.)

I use diagonal measurements to determine square corners on everything from kitchen cabinet boxes to forms for pouring a 100-foot concrete pad. It’s an extremely useful technique that’s always reliable.

That said, the only time it’s possible to square a box is before you’ve attached the bottom or back. Without the support a bottom or back delivers, you’re still free to push and pull opposite corners to change their angle. This action is called “racking.” 

The Butt-Joined Plywood Box

This is the basic design for building planter boxes, storage boxes, kitchen cabinets, benches and more. Four pieces of wood create the sides of the box, with a fifth piece forming the optional back. Despite the diverse uses of butt-joined boxes, all are constructed in the same way.

“Butt joint” is a woodworking term that describes a 90-degree connection between two pieces of wood, in which the edge of one piece is joined, or “butted,” to the face of a neighboring piece. This is the simplest of all woodworking connections, and when they involve plywood or most other kinds of sheet materials, joints completed with glue and finishing nails are more than strong enough for most situations.

Butt-joined boxes are most often made with one-half- or three-quarter-inch-thick sheet materials. Cut parts to width with your table saw or track-guided saw (see “Track-Guided Saws Make Cutting More Precise” at the end of this article). If some of the edges of the completed box will remain visible, you may want to hide the edges for appearance’s sake. Check out “Covering the Edges” later in this article to see how.