First check for wiring or plumbing behind the wall. Dont use an exterior wall. I have made them simply by making a box out of 3/4 pine sized to the stud spacing, then cutting the drywall using the box as a template. Screw the box to the studs on either side. I would then frame it with molding. A standard stud wall has 16" on center studs making the space between them 14 1/2".