Measure the height and width of the wine rack location.
Using a table saw, cut poplar to a 1-1/2" thick. Cut pieces according to measurements. Use a pocket jig to secure face frame pieces together.
Cut four pieces of plywood, following the measurements of the face frame and reducing the overall size of the body by 1/8 inch. Using wood glue and a clamp, secure pieces together; screw in place. Using a pocket jig, attach the face frame to the body.
Using the base of a wine bottle and working from the center out, mark openings on a piece of 1x4 poplar. Using a hole saw with a bit slightly larger than the base of a wine bottle, drill out holes. Repeat once. Follow the same procedure, using the neck of a wine bottle to mark a 1x4 poplar board. Drill holes using a smaller bit. Repeat once.
Cut the poplar boards in half using the table saw. Rout the edges of shelf openings with a 1/2-inch roundover bit.
To attach the shelves, drive wood screws through the sides of the unit and into the shelves. Make sure the shelves are evenly spaced and the back of the shelf is slightly higher than the front of the shelf. Nail a piece of thin plywood onto the back of the unit. Paint or stain the unit. Use wood screws to mount the wine rack to the studs in the wall.