How to fabricate a 029797 rear mudguard

[mdt-son Profile]

Hi all,

I want to fit a stainless steel rear mudguard to my 1963 G80CS. Spare part number for the 1965-68 G80CS is 029797 (mudguard was to chromed steel finish) . This mudguard is not available anywhere, to my knowledge.

I will have to buy a generic mudguard and tailor it myself. I am looking at a mudguard 5,5" (140mm) wide and 50mm high, which the shop says will fit 18+19" tires. This should clear a 4.00x19 (new designation: 110/85x19) tyre with a margin.
Actually I may have to switch to a 18" rim because of limited availability of 19" tyres.

Now, the real question is, how to I make the indentation in the mudguard to clear the swinging arm cross-tube? I want the mudguard to look as original as possible. Any ideas or advice?

Thanks,
Knut