dashcam earth near fusebox?

[Ant555]

I picked up my brand new corsa F 2 days ago - im pleased with it although there are definitely some things i'd rather be different

Anyway, ive run a dash cam wire from the top of the windscreen to the fuse box (will use Fuse 31 cig lighter fuse) but where is an easy earth screw round there? I just cant see an easy option to screw the earth onto..

Any thoughts on this would be appreciated.

Thanks