tip

[The Overclocker]

instead of having nothing around your fan holes, or buying fan hole moulding use a black power cable and cut it down the middle then stick it on (use the round sort of power cable)

[YMAN]

Good tip,
The insulation on a power cable will be too dense to
have any real effect.

What about that rubber that goes around a car door?
(The softest, less dense you can find.)