Making a rear divider or other interior panels
Most of the interior panels on my car were destroyed by leaking windows and mice. This is how I am making new ones.
I trace out what is left of the old panel, if one side is good I trace half and flip it over to get the other half.
Once I am happy with the outline I cut it out with a jigsaw with a scroll blade. 
If the panel needs holes for hanging or speakers I trace them on to the cutout and drill a hole or two to start the jigsaw blade in.
When I am done cutting I test fit the panel, trim if needed then spray paint it to help seal it from moisture. 
I have been using 1/8 ECUABOARD from Home Depot.
Most of the interior panels on my car were destroyed by leaking windows and mice. This is how I am making new ones.
I trace out what is left of the old panel, if one side is good I trace half and flip it over to get the other half.