Thanks everyone. :)
MetalMan, I'll be using the smallest spur that Tamiya do for the F103GT, which is something like 90T and in 0.6 mod tooth size. I'll then have a custom-made 45T (or thereabouts) pinion to match. I'm not sure how I'll get the custom pinions made yet, but I'm hoping RW Racing will be able to hook me up there.
As for the machining...they'll be cut by a CNC 5-axis mill. At the moment I'm waiting for a quote on the parts from a company called Penta Precision, and I believe they're able to deal with the 0.5mm radius filleting that the parts have right now. If not, then I'll just have to enlarge the fillets to 1.5mm radius...but hopefully that won't be a problem.
eMachineShop is great though! It's free like Lutach said, and very easy to use. On the downside, it's kinda limited in respect to 3D parts, and will only export DXFs, but it's amazing for free. It has a few annoying bugs too...but it's good stuff. You can even directly order parts that you've designed to be made through eMachineShop themselves, though I wouldn't...their prices are astronomical...
