Building a Police Box a.k.a. The Doctor's TARDIS
Step 8. Install the walls, head, and door
Fix one side wall and the front wall
To only one (for the time being) side wall and the front wall (minus the door) add angle brackets, three to each side evenly spaced and a couple at the bottom. Refer to the pictures below.
Fit one side wall (a removable wall, so do not add any glue or permanent fixings) and the front wall (less the door).
The front wall (minus the door) is a permanent fixture so glue can be added.
Drop the head in place
With one side wall and the front wall in place, the unit is adequately braced to take the head. Drop the head in place. It should fit neatly into the main body frame and sit on pillar pieces [A] and [C].
Install the remaining two panels (walls) but first prepare them by adding the angle brackets (fixing brackets that tie the panel to the corner pillars).
Fix the side wall in place without using any glue or permanent fixings so it is removable. Fix the back panel in permanently with both screws and glue.
Fix the top trims
Cut to length and fix the top trims to the tops of the panels with glue and screws.
Note that the two side panels are made to be removable, so take care not to glue the trim to either the head or the side pillars. In other words, just glue between the trim and the panel, as the trim will be fixed to the panel so when the panel is removed the trim will be with it (and not stuck to the head or side pillars).
Fix three 90 mm butt hinges to the door.
Because the screws are going into the sides of the plywood it is a good idea to cover the hinge part against the door with an angle bracket that could be screwed into the side of the door as well as the back face. Have a look at the picture below. The reason? I'm not 100% satisfied with the holding power of screws screwed into the side of some plywood. Then hang the door.