It is possible to use aluminium for plates, and etch them with a solution of sodium carbonate (washing soda)
Cool tip - cheers John, will look into that.

I've been reading up a bit on various techniques - I'm quite interested in having a go at generating the line-work digitally and using my CNC gear to do the etching - I put this together in Illustrator a while back:

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So it'll be a combination of old/new techniques - and seeing what happens..!