u/Eaterofallfood

I have been messing around with sandcasting things out of copper.

I recently poured an egg, I've done the rough sand with a disk grinder and 60 grit paper.

I have 80 to 10000 grit sandpaper for my drill.

I also have sheets for hand sanding.

Is there a good way to sand ovals and spheres?

Or will this be a time consuming aspect to finishing things? Any and all tips would be appreciated.