I have attached a “generic template” for one of the diffusers that I have used for Macro.
You may need to make some adjustments, depending on what type of lighting effect you are chasing. It’s a bit of trial and error so best to “test” fit etc before applying the foil.
The length of the main body can be extended, dependant on the height of your flash and the length of the lens.
This pattern is for a diffuser that will catch light more outwardly into you background. To push the light downward, adjust the angles and lengths of the sides, noting if you do, you will need to adjust length of top and bottom pieces.
I tend to use 3mm cardboard, just a standard cardboard box. You can use core flute (plastic card) however whilst this does give you a little added strength, it presents some challenges when making reflective.
Kitchen aluminium foil
Spray on adhesive
Tape – masking tape or similar works
HOW TO BUILD IT
Use template to mark cardboard and cut accordingly: top, bottom and two sides.
Mark/ label the sides left and right.
Spray cardboard with adhesive and place onto a sheet of foil, ensuring the shiniest side is face down. (Stick card onto the duller side).
Make sure that you flip one of the sides over. Remember, you want a left and right.
Allow to dry. Give it at least half an hour.
I tend to add some weight on top to help with the bond. A bread board of chopping board works well and then place something on top.
Once dry, cut around each section again. Foil may tear so scissors often work the best here. I also may run clear tape around the foil to prevent additional tearing. Fold/wrap tape over from foil side card side
Now the tricky part, putting it together. Take pieces and hold together over your flash head. Check for tightness etc. sometimes some additional cutting may be required and.or even the way you align each piece.
You will notice the top and bottom flare out. This will mean that the sides Weill need to be bent a little, depending on how much you wanted to flare out.
Take the top piece and one of the sides.
Align the parts, making sure the front edges ( where light comes out of) and use small bits of tape to hold together. This will help you align and get the “bend right”
Once you are happy, run masking tape along the joins. For added support, you could use clear tape on the inside.
Repeat for other side panel
Place bottom panel and tape also.
Once happy, place additional masking tape as required to help with strength.
I would then tape all the exposed ends. Flash head and light output area, just for added protection against rips and tears.