A mullion cabinet door is a type of door that contains glass panels instead of solid wood. The glass panels are separated by wooden or aluminum bars that create a grid pattern, similar to those seen on window panes. These cabinets serve both functional and aesthetic purposes, and are commonly used for storing glassware and cookware that can be easily seen by the homeowner. Mullion doors can be combined with other door styles to conceal some items while displaying others. They can be purchased as premade units or custom ordered from cabinet makers. During assembly, the cabinets are first constructed without glass, allowing for alternative materials like paneling or tin to be used instead.