The door parts, the dimensions and cutting detail.
A): Top rail. 150x50 (2x6) cut approximately 490mm (20 1/4") long to fit between the stiles.
B): Middle rail. 150x50 (2x6) cut approximately 490mm (20 1/4") long to fit between the stiles.
C): Bottom rail. 150x50 (2x6) cut approximately 490mm (20 1/4") long to fit between the stiles.
D): Vertical stiles. Two pieces of 50x50 stock 1160mm long (2x2 stock 46 5/8" long)
E): Acrylic sheet (plastic glass) 3mm (1/8") thick. Cut to suit
F): Plywood panel 12mm (1/2") thick. Cut to suit
G): Muntin bar (grille). In this case it is a strip of wood glued to the pane and is decorative only.

Step 1. Cut and groove the door members
Cut grooves in the members that house the acrylic sheet and the plywood panel. The grooves can be made with a router or by making multiple cuts with a circular saw or bench saw.
A): Top rail. Cut a 12mm deep x12mm wide (1/2" deep x 1/2" wide) groove along the bottom edge.
B): Middle rail. Cut a 12mm deep x12mm wide (1/2" deep x 1/2" wide) groove along the top edge and a 12mm deep x3mm wide (1/2" deep x 1/8" wide) groove along the bottom edge.
C): Bottom rail. Cut a 12mm deep x3mm wide (1/2" deep x 1/8" wide) groove along the top edge.
D): Vertical stiles. Cut a 12mm deep x12mm wide (1/2" deep x 1/2" wide) groove along the portion that houses the plywood and cut a 12mm deep x3mm wide (1/2" deep x 1/8" wide) groove along the portion that houses the acrylic sheet.

Step 2. Assemble the door
2a. Place the door members A, B, C, and D, together without nailing to measure the required sizes of the acrylic sheet and the plywood panel. Make them both 20mm (3/4") bigger than the opening so as to fit into the grooves.

2b. Unassemble the door members and then re-assemble with the acrylic sheet and the plywood panel in place.

Fix by nailing as shown in the illustration and also nail metal straps to the top and the bottom of the door for added strength.

Step 3. Add the decorative grille
Cut and glue strips of 10mm x 10mm (3/8"x 3/8") wood to the acrylic sheet (plastic glass) making a grid.

This is solely decorative and the size of the wood can vary depending on personal preference.

Use an exterior type glue that will adhere to both wood and plastic.