04-25-2014, 02:29 AM
My guess would be that the best way to create the swirl effect would be to mix up two different batches of plastic resin, one black and the other brown or two different shades of brown, and then swirl the two together before pouring them in the mold. The guy to ask about this is a fellow in Seattle who restores catalin cabinets, or used to, his name was Paul Pontrello I think: http://www.pontrello.com/radios.html
Regards
Arran
Regards
Arran