Thanks guys, the additional holes were worth the effort (and a couple of broken drill bits).
It took about three hours per wheel. They needed quite a bit of sanding and the steel between the holes is about 7mm thick. Drilling each 2mm pilot hole took around 3 to 4 minutes, but the 4mm and 5.5mm bits then powered through in around a minute each.
They look close enough to the original Dunlops to fool most people - the main giveaway is that mine have 20 holes while Dunlops have 15.
When you look at the price of replicas - Image Wheels Billet 46 alloys, for example (gorgeous though they undoubtedly are) come in at £309 + vat each. That's £1,483.20 plus delivery for four compared to £100 all in for my 'home made' alternative.
You pays your money, you takes your choice...
£370.80 each -
£25.00 each -
http://www.imagewheels.co.uk/pages/prices_billet.html