Are we talking about optimizing for performance, or about getting the same performance with a cheaper, lighter motor?
Just a few minutes with a sanding block or plane will reduce drag. I wouldn't be surprised if getting rid of the separated flow that square leading edges cause would actually make the fins lift curve steeper, allowing them to be smaller and still provide adequate stability.
People who want it to be pretty should study this:
https://charlesriverrc.org/articles...ithout-templates/markdrela_airfoilshaping.pdf
I've done this with a sort of elliptical planform, but I bet it's a lot easier with straight leading edges.
It's often handy to use a flexible ruler to draw a straight line with a pencil over the contour of what you're shaping. Look from the side, and you can get a good idea of the cross sectional shape. I found this handy when reconstructing a destroyed wingtip. Casting shadows from something straight, using a single light source, can also be helpful.
People who don't trust their judgement could at least round edges consistently with a router bit. Or glue on half-round mouldings.
People who want beveled leading and trailing edges could glue trailing edge stock together.
If you just want to bludgeon the air, there are always those hideous flying saucer things. Or Jeeps. ;-)
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