Guys what is used here from these guys for sharp egdes? they use same method for bodykit stuff also for the corners?
Thank you in advance

Silica is good for increasing the density of resin, but it doesn't give it strength like rovings do. It doesn't form a matrix, there is no way of transferring load. So really it is just thick resin behind the gelcoat, which is better than a void as voids can expand and blister the gelcoat with heat etc. But still, the gelcoat will chip easier than it would with rovings.