Step 3: Assembly - Doors
Setting aside the body for now, we'll start on the turret's doors. The eight (8) pieces highlighted in red and blue (photo #1) will form two separate components. Pieces "E", "F", "G", & "H" (in red) will form the left door, and pieces "I", "J", "K", & "L" (in blue) will form the right door.
Starting with the left door, attach the skinny half of piece "H" to the wider half (photo #2). From here, pieces "G", "F", & "E" will attach to "H" just as they are laid out (photo #3). Finishing the door can be tricky in the same way closing the body was in the previous step.
If you have trouble at the end, you can poke a hole in the center of piece "H" to manipulate the tabs using a paperclip. I used the same space to label the door "LEFT" (photo #4) so I wouldn't get them mixed up (though honestly they're basically identical, so you probably wouldn't even notice it if they were backwards). This spot will be covered by the door's arms later, so the hole and/or labeling will be concealed.
Wash, rinse, and repeat for the second door using pieces "I" thru "L" (photo #5).