Dear James: We created a master bedroom from two smaller bedrooms. Now, we want to build a walk-in closet into a corner. How big should one be, and how should we build it? —Aaron M. Dear Aaron: A walk-in closet is found in almost every master bedroom these days. This is a pretty simple do-it-yourself project because you just have to build a framed shell, cover it with drywall, and hang a decorative pre-hung interior door. Because it is such a popular feature, some builders and remodelers try to fit a walk-in closet into a bedroom or house that is too small for it. This not only looks odd but also isn’t very functional. By taking space away from the rest of a small bedroom, the functionality of the entire bedroom can be compromised. After combining two bedrooms, you should have plenty of room for a decent-sized walk-in closet. It …