FYI, my plane as without the motor mount, but wires installed weighs 550g. I printed at .48 extrusion width.
I have 2 suggestions after building. The motor mount holes do not line up with my motor, and I had to slot them. Second, I would angle the servo mounting hole to be perpendicular to the hinge of the elevon. Otherwise such a fantastic piece of engineering!
Any tips on battery mounting?
What motor did you use? I can always go ahead and make multiple firewalls to suit different ones. The current firewall has the standard quad motor pattern of 16x19mm and should work for pretty much all of them. All the ones I've printed on 4 different printers have always come out fitting perfectly. If your motor has the same pattern, you might want to consider printing a test cube to check your printers accuracy.
As for battery mounting, I was just using some velcro in the bottom of the tray. However, the velcro I have is really strong, so I've gone with a strap setup. I'll upload the STL's for the strap holders to the thingiverse page.
As for the servos, they're angled as they are for better print-ability. The benefits of being inline with the hinge are pretty negligible, and I'd bet money no one would be able to tell one way from the other when it's up flying in the air.
I think diamonds would be a good idea, except for the massive stress risers created by the corners. The circles have essentially no excess stress generated by their corners, having none, and a diamond with acute angles makes for some intense cracking. I don't know that that's an issue here, as a lot of the rib structure is for skin tension, but it is something to think about.
That was my other concern. In some areas, that kind of stress riser wouldn't be a problem, but in others, even being printed in layers it's not worth it. Better safe than sorry. Until I find something better, I'll keep using circles and ellipses. If they don't print perfectly, don't worry too much about it, the trouble areas you might run into are close to the leading edge, or further out on the wing. This plane is more than strong enough as is for flying in the air. I tried really hard to make it come apart this last weekend and couldn't even make it flex.