Here's your shopping list
1=3" PVC Coupling
1=3" x 2" PVC Adapting Coupling
1=2" X 1 1/2" PVC Bushing
1=1 1/2" x 1 1/4" PVC Bushing
1= 1 1/4" x 1" PVC Bushing

(a small piece of 1 1/2" pvc may be needed, see the 'Mods' section at the end of this article)

Some drinking straws (I used regular old 'carnival' straws, just the plain white ones and they had about a 1/4" internal diameter)

Tube of 'Weatherstripping' adhesive or glue. Found in auto parts stores or the automotive section of your local big box store. It's a black rubbery sticky kinda stuff that sticks to just about anything.

An exacto knife or scissors if you prefer and a tweezer helps also.

A little gaffers tape (or duct tape, whatever works for yea...)

No pvc glue is needed for this project and I'd suggest you not glue any of the fitting to allow for maximum flexibility anyway.

Here's your construction diagram. I'm not gonna insult your intelligence by telling you in what order the parts go together. No real reason to bang these parts together too tight, just snug them up so you can remove them to mod them later if needed. Stack the assembly on top of the 3" coupling and secure with duct tape around the seam. If you've got a piece of 3" pvc laying around and want to cut a 1" piece to glue between the coupling and the 3 x 2 adapter, all the better but the duct tape will work just as good if you don't. (If you use ANY glue at all on this thing, wait a day or two and allow it to air out well before using on a light to avoid 'overexposing' your first shot with an explosion)