Hi Keith,
Have considered that. The large gear at the bottom is helical and would be difficult to draw at the requisite accuracy from scratch.
I have experienced this when creating knurled edges on some of my parts, creating segments, then copying and adjusting angles to complete the circle.
I can buy PLA/carbon fibre filament, which I imagine would be stronger than the standard PLA which I've been using.
In short, my first option is to try the casting.
If that fails, then I might just have to improve my engineering drawing skills, or find software to shortcut the process.