First, joint compound is applied from top moving to the bottom over the corner bead (Image 1).
All of the screw holes are covered, and a thick coat of "mud" is added to the drywall seams. A layer of tape is pressed down, followed by a second coat of joint compound.
The inside corners and ceiling areas are covered (Image 2).
The rough opening created for the shelves is measured. In this case, two 1" x 12"s are cut to 52-1/4" long to create the sides of the unit.
The bottom and top board measurements are taken, and shelves are measured and cut to be 9-1/2" wide (Image 1).
Set one of the long boards on edge and nail the bottom board in place. Work down the length of the board, adding shelves (Image 2).
Add the opposing side board (Image 3), the top and a back made of 3/4" plywood.
Secure the pieces with a brad nailer.
Sand the first coat of joint compound and apply a second coat.
To support the shelving unit, install a block cut to the same height at the bottom of the front opening. This block is toe-nailed to the top of the window seat.
Set the shelving unit into place (Image 1) and lightly tapped the frame as needed for a tight, flush fit. Once it's even, use 2-1/2" trim screws to secure — three in each side (Image 2).
Wait until the second coat of joint compound has dried, then sand the surface.
Apply the final coat of joint compound (Image 3).