Yeah, PLA isn't very durable at all for this type of build, especially since it is so heavy!

Here is an Ultra-Light 18650 holder i designed a few weeks back: https://www.thingiverse.com/thing:4900464
Using TPU, its 6 grams!

A few things that come to mind:

• 3 to 3.5" Props would really extend the flight time but at the cost of some throttle response.
• You've a few screws that are much longer than needed. This adds weight and makes the connection of parts suspect if the screws are not pushed completely thru. (Such as with the forward motor)
• Due to the weight of the quad you could use Nylon screws to connect the motors to the frame. This should save an additional 2-3 grams.
• Inverting all of the motors should allow for greater efficiency as the thrust doesn't have to contend with the frame being in the way. It's not like your going to tilt forward much if your just cruising around so prop-wash shouldn't be much of an issue.
• Plus frames can run different sized props on the arms allowing you to have better throttle response where needed. Ideally, smaller 2.5" props front/back and larger 3-3.5" props left/right. This will allow for much better response overall.

Here is my latest build: https://rotorbuilds.com/build/27673

I think adding an airfoil type shape to the arms could be a really cool idea. I think for now I am going to take a break from this style of frame but that design would be quite interesting!

Very cool design Polymerization! Funny that Ingustol has mentioned this because I've printed out Daves base nano frame but its not my type of quad flying, a plane however lol Its much more work than I have the abilities to do but was taking inspiration from Elecronoobs fully 3d printed Yak linked below but yeah I dont have it in me but man a micro 3d printed plane using 18650's would be pretty sweet. http://electronoobs.com/eng_robotica_tut11_stl1.php

https://www.youtube.com/watch?v=xzMnm3DunUY&t=582s

wow that plane looks awesome, yeah I think a lot of work will have to be done to make function partially like a plane but could also offer an increase in range.

I came to multirotor after 20+ years of fixed wing and understand what you are talking about with having a lifting wing airfoil shaped design as Igustol mentioned you would have to be able to rotate the rotors in the direction of lift, as thrust in any other direction would prevent any lifting effects. Still this is a great 18650 nano build youve made here. I'd bet if you shared the stl there will be others trying it out. When I purchased some of single 18650 trays, I also purchased a few double trays and will be trying to mount them in a few foamy planes down the road but doubt any will be rotorbuilds worthy ;-(

Thanks for letting me know haha, sorry about that. They should be public now!

And there they are! Looks like it's flying well, a bit of a tune notwithstanding, and plenty of time in the air! Nice work. Splendid design, and a great project, I like this very much.

So the Plus frame builds I have are rather twitchy in the roll axis, and they are 5" machines not teeny things like this, so this is likely just a characteristic of this geometry - it is visually very nifty though, and the machines do move in an interesting, somewhat sinuous manner.

More or less I used the same wiring and general idea of the original NanoLongRange for it but you can find more information on the video that I have on the page. I also recorded some footage on the construction and design of it which I will upload it in the coming weeks on my channel but if you have a specific question I can try to answer it!