Not sure if this is a serious question or not, but I don't see the point.
Obviously there has been a historical healthy debate on this forum about whether you need to carry proof of registration paperwork with you. There are essentially two camps of divided along the lines of "screw anybody who asks me and I will take a felony arrest if I have to" and "It not a huge burden to be polite to inquiring LE and save me the hassle, potential arrest and property seizure". That said, I don't think we have ever nor will ever arrive at a consensus on the commonly accepted "correct" approach. YMMV
However, carrying copies on microfilm that nobody can read on the side of the road just seems like you are taking the disadvantage of both positions. i.e. Dealing with the hassle of carrying around a role of microfilm and if you are ever stopped the law enforcement officer probably can't read it anyway so the microfilm is probably close to worthless to prevent hassle or arrest. You might honestly come off as more of an ass (or just plain crazy) handing over a roll of microfilm to a State Trooper, so it might be better to just carry nothing at all and tell them you you left your paperwork at home.
Me personally... I like straight up full size paper copies. They always work as they don't require a cell signal, a charged battery, or a functional handheld device, etc. Full hard copies in a nicely organized binder, imho look the most professional/legitimate when trying to convince a potentially skeptical officer that all these scary looking exotic guns are legal. I also am not thrilled with the idea of potentially handing over my unlocked phone to LE who is going to have to try find the right .pdf file out of 75 odd files and also have to zoom around an original ~8.5"x11" document on a ~4" cell phone screen. With full sized hard copies in a binder an officer can easily navigate all of my paperwork without my assistance if worst case I am sitting handcuffed on the curb.