OK. 13Mb stl file with job as it is currently.

https://www.dropbox.com/s/yndin6qwcb...r_WIP.stl?dl=0

If anybody does decide to give it a whirl I'd be very grateful for comments and ideas on where to go with this.

Some notes:
Slicer settings. 0.2mm nozzle height and standard O.4 mm nozzle. As I said, Z-hop enabled; I've set it to 0.2 for these thicknesses, it'll need to be higher if we can get the two-layer version working.
I slice with a skirt to help purge the previous colour filament. Works well for all colours except the blue that I use which seems to need much more purging so the gold that follows isn't contaminated.

Strange layout of the individual stl files is because I find that the file selection on the Ender is a real pain when there's more than a couple of files to choose from. So I Have A and B directories on the TF card with 1, 2, 3 and 4 sub-directories to hold the gcode files.

My order of printing. Black, White, Green, Brown, Red, Blue and Gold. Then the final white 'cover' print.
Don't forget to peel off the purge-line, skirt and 'register box' between each colour.
I don't have much of a stringing problem but I do use a soft brush after the first black print to make sure that the following white print is nice and clear.

Enjoy,

Chris