Hi Steve, here's a photo of the finished camera - it just needs a viewfinder which I'm waiting for. I'm off out now with my test film inside, having just recalculated the f stop markings.
Thanks David. Steve, I've sent off for a Gaoersi viewfinder, the 90mm fixed viewfinder for 6x17 should cover the same area as I need for the Nimslo.
I've developed the second test film and all the exposures are looking good, so thanks to everyone for their help. Heres a rough scan of one of the frames...