Agreed there. I tried to 3d print some props for a TinyWhoop; the suckers were HORRIBLY unbalanced. I was initially trying to do it for cheap, but when I realized that it was taking 2 hours to run a print of ONE prop and the prop wasn't balanced right, I said "Forget this, I'm better off buying a set of props at $4/package."
The only way I'd use a 3D printed prop is to get a prototype. Once I had that prototype balanced and everything, I'd maybe try to make some molds, but there's no way I'd trust a straight 3D printed prop.