Flashlight with Conductive Filament - Limited Success - Learning Experience

I was attempting to design a simple flashlight using conductive filament with the goal of being entirely printed (just add batteries and bulb) with a single extruder 3d printer. The following photos and files are the culmination of a few rounds of prototyping with non-conductive filament just checking for fit, followed by several rounds with conductive filament, culminating in a technically successful (it produced light) though practically failed (it barely produced light) project.

The design revolves around a color change in Prusa Slicer. By printing all the pieces of the flashlight laying horizontal, I inserted a color change at approximately every third in height of the print for the caps, and just the top few layers of the body. The premise being to swap out the conductive filament at the change, allowing it to act as the wire/conductor of the flashlight. As you can see in the photos, this would allow for one of the caps to be loosened or tightened so the conductive (dark) filament would contact/not-contact, effectively acting as an on/off for the flashlight. 

The first hurdle in this method was getting the length of the body right so that the batteries or bulb would not be too aggressively crushed while making contact, and the conductive filament being lined up at the right point of pressure. With a bit of tweaking this was accomplished with reasonable success.

The initial models used 2 AA batteries in series for 3v, and a standard 3v led flashlight replacement bulb. However, the resistance of the filament proved too great to effectively light the bulb, and it barely even turned on.

Ultimately a change to 3 CR123A batteries were used in series for 9v, as well as a 5-24v led flashlight replacement bulb. The other necessary change was to increase the amount of conductive filament used to help increase conductivity. So the walls and caps were thickened, and the caps and body were changed to more of a 60% non-conductive, 40% conductive split. This again was achieved in the slicer by simply choosing a color change and swapping out for the conductive filament at that point. I also found the spherical button style contact for the battery end cap I initially used was not as effective as a flat cylinder button. The cylinder greatly improved contact with the battery and reduced dimpling or crushing of the battery end.

This produced better results, but not quite what I was hoping for, if I was stuck in a mine and had nothing else, sure, but a match or lighter would be brighter.

So what did I learn? 

Well, the Protopasta Conductive Filament is not near as conductive as I hoped. Any design that requires the current be carried any distance will suffer from resistivity. On the final model with the thicker wall the body still measured 350 ohms resistance across its length, and depending on how well the threads and caps bite and lineup anywhere from 500-3000 ohms across the whole flashlight.

For future design considerations, I would use the battery as the conductor along the length of the body and only have conductive ends, or use batteries with conductors only on one end. Basically, any future designs need to address reducing the distance the conductive filament needs carry the current.

If you have any questions let me know.