Thanks a lot for this! I've been looking at learning how, but I haven't been able to find a vid. Is that block just a sanding block? And it's wet-or-dry sandpaper, right?
Actually, I don't recommand adding water on the helmet with a sponge. If you haven't resined or fiberglassed properly (aka air bubbles) the water will get the paper more weak. I also recommand putting a t-shirt or you hand inside the helmet while sanding to avoid warping the helmet with too much pressure.
@Dark Rouge:
Yes the block is a rubber/foam sanding block. And you have to use wet sandable sand paper. If you use dry it will fall apart. The black can usually be used as wet sand paper.
@LastSpartan:
Yes you should only put water on it if you know it is fully water proof and don't use to much pressure or you will warp it.