I have several 4000 desktops in which I have had a number of the front panels along with other bits and pieces professionally sprayed with a special paint that sticks to acrylic. The machine come up like new amd it is impossible to tell they have been resprayed. I also have a mint old 2000 in which I fitted a Cream CD drive. I got that resprayed the same tan colour of the 2000 and it looks really good. Other items I have applied the same treatment too are yellowed drive bay surrounds, floppy drive fronts, amiga keyboard surrounds etc etc The transformation is fantastic! I am not sure what the paint is but I could make inquiries if you are interested. I certainly would not sand the panels. The only hassle is you have to disassemble everything but it is worth it. I am just about to apply the same treatment to a 3000 and 1200 case surround. The fact is I Hate yellowed and mismatched amigas!!!
