i have no idea why folks think fiberglass has durability issues, if were talking about hand laid hobbyist grade fiberglass matts maybe, but technology has comes leaps and bound from there, fiberglass, if fabricated right with the correct stabilizer and UV protection can be a high grade material
@steelbox
i highly doubt they would make a laptop chassis out of sheet metal aluminum (in the main presses are used in sheet metal fabrication) might work for an iPhone4 but not a laptop, it would be a pressure die cast aluminum chassis and no matter how good a process you got your still going have to do some machining for interface fit and holes
cost is rarely on material alone, fabrication time and tooling cost is a factor too, if we talking about 10's of 1000's of parts then fiber glass makes sense, but if we talking about 100's of 1000's of parts the the high cycle time for die cast aluminum becomes more cost effective
@burnley14
the chassis should never be designed as a heatsink, it's primary role is to absorb and dissipate stress loads, using it as a heat sink would diminish it's ability to handle stress loads