I've never tried taking a screenshot of something where one of the colours has been replaced with copper-generated lines, but I guess that the copper-generated bits just come out as a flat colour? If so, why not take a screenshot normally then send that and the details of the copper list to someone with UAE - presumably if they set up the screen identically they could get the copper adjusting the "right" colours of the palette and reconstruct it that way in order to take a screenshot? This better look good though :-D