This a multi-segment diffuser for the 350Z rear bumper. This design will make 6 strakes to fit between the stock exhaust.
This fits 2003-2005 cars for sure; don't know about later 350Z models or 370Z...maybe?
I'm hoping PLA won't warp since this is located so low on the car and in the shadow. But won't know until I try. I may have to paint it silver to match the car to prevent warpage.
As for the endpiece - I had a print of the main part that ran out of filament after the "spacer" portion was 56mm wide - so I created a mirror-image piece that has the spacer on the other side and is 39mm wide to make the total 95mm spacing -same as the other pieces. Just print one of these to make the left-hand end of the diffuser.
In conclusion you should print 4 entire diffuser pieces, then a fifth one you stop after the spacer is 56mm wide, and then one of the endpieces to make a 6 strake diffuser.
I used cardboard to cut a template that fit the car. I then took a photo of that template, fed it into photoshop then into sketchup. I then traced it and created a 3D object. Fits great!