Measure the width and height of your cabinets. If your cabinets already have doors, measure their dimensions to use as a template for your new doors. Remove the doors by unscrewing the hinges with a screwdriver and remove them from the frame.
Cut a sheet of one-half-inch plywood using a jigsaw for the main structure of your cabinet door. Cut the door to about 2 inches less than the height and width measurements you just took.
Use the jigsaw to cut four pieces of 1-by-3-inch hardwood to assemble a frame for your cabinet door. Cut two pieces using the width measurement you took earlier and two more pieces using the height measurement minus 6 inches.
Arrange the four pieces of hardwood in a rectangle shape, sandwiching the shorter pieces between the ends of the longer pieces. Secure the frame by toe-nailing nails from a nail gun through the pieces of wood at the joints.
Apply a generous bead of wood glue around the edges of the sheet of plywood, then lay the rectangular frame you just assembled on top of it. Center the frame over the sheet of plywood and press it gently into the glue. Flip the frame over and drive nails from the nail gun through the back of the plywood into the frame.
Draw a template on the back of the sheet of plywood to use as a guide for your cutout. After you cut out a portion of the plywood, you will install a sheet of glass inside the cabinet door so you will be able to view your glassware. The shape of the cutout is up to you, but a rectangular shape is the easiest to do.
Use a reciprocating saw to cut out the template you just drew. Remove the cutout and gently sand the cut edges of the plywood with a piece of fine-grain sandpaper.
Have the professionals at your local hardware store cut a piece of one-quarter-inch sheet glass to the interior dimensions of the 1-by-3-inch hardwood frame. You may choose whether you want to use clear, frosted or textured glass.
Set the sheet of glass inside the hardwood frame so it rests flat on the plywood panel. Screw glass clips into the back of the cabinet door frame every 12 inches to hold the glass panel securely in place.
Paint or stain your cabinet door to match the rest of your cabinets. Install the doors using metal hinges placed at the same interval as on the original doors, so you can either reuse the old hinges or the pilot holes from the original hinges.