I'm assuming that machines are used to spray the rads, ensuring an even layer all around. With rattle cans or any other method by hand you will most likely get an uneven finish.
yer i agree that paint can dont get you good even coverage and you do get quite a bit of orange peel but you have to flat back the orange peel hen you paint with a spray gun aswell. when flatted back and polished up tho you can get very good reflections and results
such as (sorry for the bad phone pics)

every time i tried to use the multi quote botton it just did the same as the quote bottton and would not let me multi quote