Building a Police Box a.k.a. The Doctor's TARDIS
The TARDIS roof lamp
• Roof lamp introduction
• Roof lamp plans
• Sourcing the components
• Making the lamp cap
The lamp container base
For this use a piece of 24mm (1") thick plywood 137mm (5 3/4") square. Maybe glue two 12mm (1/2") thick pieces together to get the required thickness.
Also a short length about 64mm (2 1/2") of PVC pipe with a diameter slightly smaller than the inside diameter of the fresnel lens. In this case, 76mm (3") diameter.
Drill a 76mm (3") diameter hole in center of the plywood base piece and glue the PVC pipe in the hole, protruding 3mm (1/8") out the top side and the rest hanging out the bottom. I used an adhesive sealant that would grip to both the PVC and the wood.
While waiting for everything to dry, drill a 76mm (3") diameter hole through the middle of the apex square at the top of the TARDIS.
Make a hole template for the threaded rod. This is to mark all the necessary holes in the cap, base, roof, and light platform. Having a template ensures all the holes will be aligned.
On a piece of card mark three circles.
1 @ 86mm (3 3/8") diameter - the overall width (diameter) of the PVC pipe.
1 @ 106mm (4 1/8") diameter - the overall width (diameter) of the fresnel lens.
1 @ 135mm (5 5/16") diameter - the overall width (diameter) of the lamp cap
Draw a cross from the middle and mark (on the cross lines) a point 3mm (1/8") past the middle circle (the overall width (diameter) of the fresnel lens).
Cut out along the lines of the most inner and most outer circles so you end up with a rim approximately 25mm (1") wide.
That is the template to mark the holes for the four threaded rod pieces (the rods that hold it all together) on the cap flange, the base of the lamp container, the apex of the TARDIS roof, and the light socket support platform.