Clean the door blanks with fine-grit sandpaper and a polishing cloth, or in a tumbler for 2-3 hours.
Find a pleasing portion of the Christmas tin, that fits in the window of the door blank. Draw around outside of door blank with fine-point permanent marker. Cut tin with shears.
Stamp stars randomly on the front door panel, and add texture as desired with the rounded end of a ballpeen hammer. Stamp or hammer a design or pattern on the back too.
To make your pattern stand out, antique the brass pieces with Win-Ox. Dry thoroughly and polish as desired. Don't wait until the end to antique your design, as you don't know exactly what the "tin" is made of.
Sandwich the tin between the 2 pieces of the door blank, align edges carefully, and hold bottom half in place with Ring Clamp. Wedge clamp firmly to hold tight.
In one top corner, punch a 3/32" hole through all 3 pieces. Slide a 3/32" diameter 3/32" long eyelet through this hole, and use the 3/32" eyelet flaring set to secure it. Repeat for other other top corner.