Set two 3/4-by-36-by-36-inch plywood boards parallel to one another, standing up on one of their thin ends. Position them about 2 feet apart to be the sides of the pantry unit. Set a 3/4-by-24-by-36-inch plywood board against one of the ends to serve as the top board of the pantry unit.
Drill a series of holes spaced 6 inches apart through the top board and into each of the side board ends. Set 2-inch wood screws in each of the holes and tighten them securely to fasten the top board to the side boards. Repeat with another 3/4-by-24-by-36-inch board to serve as the bottom board by screwing it into the other end of the side boards.
Use a 3/4-by-24-by-37 1/2-inch plywood board to cover the frame of the pantry unit. Drill a series of holes spaced 6 inches apart through this board, which is the rear board, and into the frame below. Fasten the rear board in place with 2-inch wood screws in each hole.
Flip the frame upside down. Cover the frame with another 3/4-by-24-by-37 1/2-inch plywood board. Position two side-mount cabinet hinges between one of the side boards and this new board, which will be the door.
Mark the hinge attachment screw holes, lifting the door board if necessary. Remove the hinges and drill out the holes. Fasten the hinges to the door and side board with 1/2-inch wood screws.
Position a knob against the front of the door and mark its location. Drill a hole in the marking and slide the knob bolt through the hole. Tighten the nut on the bolt to attach the knob in place. Hold a magnetic latch up to the side board and drill holes for the screws.
Attach the magnetic latch to the side board with 1/2-inch wood screws. Line up the other half of the latch with the door and repeat to install the other half of the latch on the door.
Stand the unit upside down so its bottom board is in the air. Drill a hole in each corner, directly into the rear board or side boards. Screw a wheel into each hole by hand tightening them.
Set the unit right side up and position a 3/4-by-22 1/2-by-36-inch shelf board inside the unit at the desired shelf height. Have an assistant hold it in place and position two 1-inch L brackets under the shelf against each side board.
Mark the position of each screw hole. Remove the shelf board and drill out the holes in the shelf board and side boards. Replace the shelf and screw the brackets in place with 1/2-inch wood screws. Repeat as needed for additional shelving.