They're using the farraday cage way of removing interference. Sometimes it works, the issue is how big the gaps are. It's often used for excluding radio types of interference from high precision scientific instruments.
If you were to attempt this, you might be better off with a light gauge wire gauze.
97 VW Jetta - building a system from parts in my old 85 Jetta
HU: Pioneer P740MP with 12 disc changer
Front: 3.5" JBL GTO302s in dash
5.25" Cerwin Vega Vega Series 502s in door
Amped: US Acoustics USX-2050 @ 2 ohm
Rear: Stock components
Sub: Single 12" Vega 124 in a cheap bandpass box
Sub Amp:US Acoustics USX-2150 bridged