How to Build a Box

Think “inside the box” to build cabinets, shelves, window boxes and more.

| February/March 2012

Terminology Illustrated

Outdoor projects, too, can benefit from your box-building knowledge.


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.

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