The more I read about the NFC tag and the various forums (of which there are precious few I've found) regarding the DaVinci Jr., I'm quickly coming to the conclusion that any means of getting rid of the filament restrictions begins and ends with the FIRMWARE. I'm convinced that any NFC hack is going to be difficult at best and outside of the means/abilities of this printer's target market - casual users/newbies. So far as I can tell, any significantly robust NFC hack will, at best, require ordering and encoding NFC tags which, in turn, also require the purchase of hardware to handle writing those new NFC tags. Not that this would be particularly difficult once the tag format is cracked, but still outside the abilities/comfort zone/desire of newbies.
Further, just dumping the XYZ main board and throwing a RAMPS or the like at it, while entirely feasible, would also eliminate the target market. Granted, 3D printing isn't exactly for the faint of heart, but this printer is marketed as "plug-and-play" intro-level printer with, at least, decent capabilities that is comparatively easy to use. The NFC system DOES, in fact, lend itself well to that purpose. But we all eventually get bored printing vases and only printing with one material.
I believe the best way to still include the target market while giving folks a way to have the printer grow a bit with them is a "drop-in" replacement for the firmware. The really "green" newbies can still use it as intended with NFC in-tact with stock software but, when the newbies start becoming a bit more adept and want to branch out a bit, a simple firmware "upgrade" would make all that pretty painless and open up a whole new world - new softwares with much more control and new materials with properties suited to new purposes.
I'm not even going to front on this - I want NFC broken so I can order cheaper/better filament from companies that aren't always out of stock. But I also want a bit more control over the printer. I want to use ABS. I want finer control of shell thickness, infill, and layer resolution. From what I've seen in other softwares, there's a TON of options giving users hundreds of control parameters to tweak to their heart's desire. I don't need all of that right now because I'm just getting started myself. I just want a *little* more control for now. Given a firmware solution, I believe this printer can grow a bit with me. I know it'll never be as good as many other printers on the market. But it should be "good enough" to give me some wiggle room while I climb the learning curve.
All that being said (and, trust me, I know I'm a bit long-winded), I truly believe we should be focusing on the firmware instead of the NFC system. Now, I don't know exactly how to go about that and I won't even pretend to. I have some experience with programming, uControllers, and even a little bit of FPGA development. ARM dev really isn't my game so all I can really offer there is my support. But I'm willing to help out in any way I'm capable!
My sincere thanks go to everyone here working on this and I hope we can get this working soon.