Well, I know that Li -Ion may not the best as a power supply but I have made a 3 x 18650 mod anyway
It features
- 3 x LG HG2 3000mAh batteries with a whopping 33.3Wh nominal and hopefully some 25-30Wh actual capacity which is still not too bad especially for the size.
- Max planned dimensions of 38 x 50 x 85mm (1.496 x 1.9685 x 3.3465 inches) with an annoying +/-0.5mm Shapeways tolerancy
- Thousands of parts
including:
- Slightly concave battery cover that even more ergonomic (at least for me) than expected
- Spring loaded solid copper battery contacts
- Additional 25A quick blow glass fuse
- Pressfit concave fire button that almost works as good as intended and almost always as flush as designed

- Super simple double action +/- bar that works/looks exactly as intended
- A 3D print with acceptable overall accuracy and unacceptable accuracy on detail level (e.g. the body is some 0.5mm higher than designed which is ok but this 0.5 mm is plenty when it is added to a wall that should have been 2.5 mm thick not 3mm) and a broken(?)/missing part that happen to be an extremely important load bearing screw socket. Let alone the useless oval pilot holes just to name a few.
- A couple stupid design flaws including a missing pilot hole where I couldn't drill any
- Some brutal filing/hot knifing etc. actions and yes, even some hot glues thanks to the last two points above.
It doesn't features the designed magnets thought because of the useless oval sockets and the super tight fit that I finally achieved when I managed to file/grind enough material off to make the parts interlock at all.
All in all, it is working and fits nicely in the colourful fleet
And this is how it started; a broken battery pack that I was playing with: