Plan and Diagram the Dimensions of Your Project
Plan and draw a diagram of the storage unit in the desired size that will fit under your bed. The finished box on wheels must be fractionally lower than the available under-bed clearance (in this project, the clearance is 6 1/2 inches). Purchase the required materials and assemble your tools--these will include safety glasses and, optimally, a dust mask because you will be using power tools and cutting lumber.

Use a Power Saw to Cut Four Sides for the Storage Box
Use a power miter saw or chop saw to cut four sides for the storage unit. We used one-by-sixes cut to measure.

Install a Stacked Dado Set on Your Table Saw
Install a stacked dado set on your table saw in preparation for making dado joints for the corners. We used three blades to make a wide notch.

Cut Rabbets on the Ends of the One-by-sixes
Cut rabbets on the ends to interlock the cut-to-measure one-by-sixes to form the corners of the box. Sand them if necessary. You will join them into a box in a later step.

Install a Narrower Dado on the Table Saw to Cut Grooves for the Plywood Bottom
Switch to a narrower dado to cut grooves to accommodate 1/4-inch plywood along one long edge of each one-by six. Later, you will slide a plywood bottom for the storage unit into these grooves.

Apply Carpenter's Glue to the Rabbets
Use a brush to apply carpenter's glue to the rabbets on the ends of three of the four one-by-six sides.

Fit the Rabbets on Two Sides of the Box Together
Stand two of the one-by-sixes on edge, oriented with the long grooves on the lower edge, and fit the rabbets together in a glued corner joint.

Add aThird Side and Clamp Them Together
Add the third one-by six and then clamp them together with wood clamps.

Secure Each Joint with a Pin Nailer
Secure each joint with a pin nailer. Wait to add the fourth side.

Slide the Bottom Panel into the Grooves on the Three Sides
Slip a one-piece bottom panel cut to measure from 1/4-inch plywood into the long grooves along the bottoms of the three one-by-six sides.

Seat the Panel by Tapping Against It with a Small Block and Hammer
Tap with a hammer against a small block placed at the open edge of the plywood panel until it is seated in the grooves.

Apply Glue to the Rabbet on the Last Side
Apply glue to the rabbets on the last side and attach it. Do not apply glue to the bottom panel anywhere, because it may expand and contract with temperature changes.

Mount a Large Hole Saw on Your Drill Press to Cut Wheels
Mount a large hole saw on your drill press and cut four wheels from scraps of one-by-sixes. The wheels will be the cutout pieces from the hole saw.

Drive the Purchased Axles into Caps for Hubs
Drive the purchased axle components into the caps for each wheel, setting the caps upside down and gently tapping the axle in with a hammer.

Mount the Wheels on the Axles and Add Metal Washers
Add a large metal washer to the assembled cap and axle, mount the wheel, and then add another washer or two to space the wheel off the box to prevent rubbing. Position and pre-drill two holes for the wheel axles on the sides of the box (as opposed to the front and back). The holes should be the same diameter as the axles and only as deep as the exposed length of the axles.

Apply 5-Minute Epoxy to the Exposed Portions of the Axles
Use a small paintbrush to apply fast-setting 5-minute epoxy. Coat only the last 1/4 inch of the axles and avoid getting glue on the washers.

Insert the Axles in Pre-drilled Holes on the Sides of the Box
Insert the axle of each wheel assembly into one of the pre-drilled holes on the sides of the box. You will need to elevate the body of the box temporarily while you attach the wheels.

Tape the Wheel Assemblies in Place Until They Dry
Tape the wheel assemblies in position temporarily until the glue dries for the required 5 minutes. Remove the tape.

Drill Holes for the Drawer Pulls
Drill a pair of holes in the front of the storage unit for each of two drawer-pulls after measuring the distance between the two screw fasteners and marking the positions on the drawer appropriately.

Mount the Drawer Pulls from the Inside of the Box
Insert the screws through the holes and into the drawer pull from the inside of the box and tighten them until snug. Mount the second drawer pull in the same way.