Want some protection for your highly flamable and potentially explosive LiPo battery when your quadcopter crashes? You're in luck! Having dented a couple of my batteries from making emergency landings from several meters from the ground, I decided this fragile part of the quadcopter needed a bit more protection.
This is a rigid casing for batteries sized up to 25mm x 50mm x 150mm. Designed to fit flush over the screws of a Warthox Quadcopter frame and attached with long strips of velcro to the frame.
Using a 0.5mm nozzle with a 0.2mm layer height and 280-300% extrusion width, the total weight of the case came up to about 100 grams. Bit heavy, but lots of protection for the battery.
Also, the triangles at the sides allows you to attach these landing legs to the casing. http://www.thingiverse.com/thing:89154
The frame it's designed for; http://flyduino.net/Quadrocopter-Frame-Set-20cm-arm
The battery it's designed for; http://www.hobbyking.com/hobbyking/store/__9957__ZIPPY_Flightmax_4000mAh_3S1P_40C.html
Print the case vertically.
I'd use a higher than normal extrusion width, or at least increase the extrusion multiplier to 1.1 or 1.2, so that each layer is fused to the other more firmly. It wouldn't be the prettiest result, but it'll be stronger.
I used a hexagonal infill at 50%, to save on weight, you might get away with less, but I wouldn't push it too far if you're planning on crashing a lot.
When you're done, simply thread the velcro straps through the supplied gaps horizontally and vertically and make sure it doesn't wiggle around too much.
If your battery rattles around in the case, I would recommend padding it with some foam or bubble wrap.
After several hard landings onto concrete, my case delaminated along the layers, I was using PLA, maybe it'll be a bit more impact resistant with ABS or Nylon.