I was gonna make my custom diffuser a long time ago, never had time. Finally I found some spare time last week. I was working on it for about 5 days, 5-6 hours after work, put about 30 hrs into making it and using basic tools and materials that can be found at any Walmart such as:
- plastic board (1/4" x 48" x 72") $20
- 1gallon of fiberglass resin - $40
- set of brushes - $10
- 2 cans of truck bedliner - $15
- hardware - $5
- brewskis

I used 3 5/16 long bolts to mount my diffuser to the spare wheel compartment and 6 screws to attach it to the rear bumper.
The diffuser is very sturdy and fits like a glove.
All under 100 bucks.
I might be making another one, with differently shaped fins....not sure.
Anyways, enjoy the pictures!

 

 

after applying bedliner

 

 

INSTALLED!!!!!

 

 

Awesome

 

Hey Java..diffuser looks hella clean! DIY FTW!

 

Dam this is nice, might try this on the fozzie

 

It's not hard at all. Once you take all the measurements and make base of your diffuser, attaching fins is a cake

 

Ile take a look under the forester tomorrow and possibly get back to you. It would be rly cool to have one, never seen a aggressive rear diffuser on a forester

 

So you just used fiberglass resin as a glue all over the part? No actual fiber mat was put on it?

 

I used mat to attach fins to the base.
Believe me, it's more sturdy and has better mounting points than some $500 diffusers. 2 coats of bedliner made it rock hard.

 

looks awesome man. you are a great craftsman my friend.

 

Looks amazing! we should trade you make me one and ill photo shoot your car lol