Remove the existing doors from the cabinet by unscrewing the hinge from the cabinet jamb, using a cordless drill and Philips head bit.
Mark the bottom of the cabinet interior, 1/8 inch in from the open edge, with a 1-inch thick penciled strip from the left side to the right side. Make the strip parallel with the opening of the cabinet.
Adjust the cordless drill's depth gauge to 1/2-inch depth. Drill 1/2-inch holes inside the 1-inch strip using the cordless drill and a 1/2-inch boring bit. Make the holes touching each other, in two rows inside the penciled strip.
Use a chisel to square off the boring holes inside the strip. Smooth the strip with the chisel by striking the chisel handle with a mallet to remove debris and rough edges inside the strip.
Insert a metal dual set runner inside the strip. Flatten the runner inside the cabinet by gently pounding the runner with a mallet.
Drill and chisel a strip into the top of the cabinet interior with the same measurements. Insert a runner into the top of the cabinet as well.
Attach a 18-by-24-by-1/2 inch metal glass frame kit around two panes of 18-by-24-by-1/2 inch glass. Attach the plastic brackets to the corners of the glass panes. Insert the ends of the brackets into the metal frame edges. The metal frame edges are 1/8-inch wider than the actual 18-by-24-by-1 inch the kit claims.
Set the glass doors into the runner. Set one pane into the further edge of the runner by holding the pane at a 45-degree angle and sliding the bottom edge, a 18-inch side, into the bottom runner. Push the top edge into the top runner. Repeat this process for inserting the second, front pane.
Place a magnetic door knob on the front pane and use it for sliding both doors.