Building a Police Box a.k.a. The Doctor's TARDIS
Step 5. Assemble and stand the frames
Fix the infills [G] to the sign holders [E].
On a flat surface, assemble and fix the front and rear frame units each consisting of two pillars, an infill/signholder piece, and a floor board.
Then stand the front and rear frames units in place in the base frame. Screw the floorboard of each frame unit to the base frame and middle joist so that the screws can easily be extracted if the Police Box ever needs to be taken apart.
Fix the side infill/signholder pieces to the front and rear frame units.
Screw the infill/signholder pieces to the pillars so that the screws can easily be extracted if the Police Box ever need to be taken apart.
Place and fix the remaining floor boards.