It is a very simple instructable.
The pictures are pretty much self-explanatory.
Step 1: Scoops.
Get some scoops from milk powder, detergent etc. Cut off the handles.
Step 2: Fitting.
I use bicycle inner tubes to make sure the scoops fit nice and tight.
The makeshift diffusers are not suppose to fall out even when the flashlight is hung upside down.
Step 3: Plug and Play.
Attach the scoops and ...... Viola! Your DIY flashlight diffuser for free.
You can use different colored scoops for different effects and uses.
Red scoops are useful for preserving night vision.
Yellow scoops with blinker warns other motorist of road hazards.