CD template...

[Gandalf]

I heard that a CD was the perfect size for a 120mm blow hole?

Is this true?

[Ottoman]

yup... the cd is the same size and the prop...

[Mike K]

it is not exact. A CD is slightly larger radius that 120mm.

[Tbird man]

guess what else, the pocket (8cm) cdrs work perfect for 80mm.

[Diggrr]

Actually, CD's run from 119.5 - 120.5 mm. It's the fans that aren't exactly to size. My Panaflo 120mm is actually 112 across the blades. (digital calipers)

But yes, a cd makes a great template, just cut on the inside edge of the line. Better still, draw the cd outline and put your fan on it to compare.