I am building some shop cabinets that will be 30" wide, so with side mount slides, each drawer will be 29" wide. I will alter install overlay drawer fronts as there will be no face frame. I want the drawers to be different sizes, say maybe 9", 6" and 4" or some combination. Ideally there would be two 4" drawers for a total of 4 drawers. Any quick tips for measuring exact sizes and optimal hights/spacing between drawsers?