This diffuser efficiently spreads the highly directional beam of a flashlight inside using a double-cone structure, preventing the light from shooting straight out. Flat surfaces prevent the flashlight from rolling when laid on its side, and its parametric design allows it to fit your flashlight perfectly.

Parameters:
This design can be adjusted in Fusion 360 (the free version is sufficient) to fit flashlights with head diameters of approximately 30–50 mm. Download and open “Parametric_flashlight_diffuser.f3d”, then go to "Solid" → “Modify” → “Change Parameters” to adjust the settings.

Only one parameter needs to be changed: “id”. Measure the head diameter of your flashlight accurately with a caliper. Apply adjustment: TPU = value −0.2 mm, PETG/PLA = value +0.1 mm. Enter this in the “Expression” field and click OK. The model adjusts automatically. Print a small test piece first to check the fit, then fine-tune as needed for a perfect diffuser.

Notes:

• I recommend printing in white TPU or PETG filament.