I'm looking at doing some car body panels which I'd normally lay up with 1x200g / 3mm soric / 1x200g.  Thought I might look into other cores as the general consensus is that soric can be a little heavy.  The reverse side finish is also quite poor as the cells show through quite strongly.  I've been considering core cork as an option as it looks pretty smooth on both sides.  For those that have used it can I ask id 1x200g would be enough of a skin with this core?   Any others I should consider?

I have built many of parts with just 1 x 200g and foam core. Only down side is that the foam can dent when hit or knocked too hard. 2 x 200 would make a big difference to that although x2 material, weight and cost of course. This is why I say use 100kg min. A cork core will dent much easier too.