I'm pretty sure you could print out a 2.5 x 3 inch copy of your Facebook profile photo and it would be fine.
Missouri's application is pretty silly. I started to fill it out but ended up taking it in Kansas instead, largely because of how much easier it was to collect the required documentation in Kansas. For the Missouri application I needed to attach that photo, three experience reference letters from former supervisors, three professional reference letters from other engineers, two personal character reference letters... eight letters total, all of which needed to be in signed/stamped envelopes and mailed together with an affidavit which needed to be witnessed and sealed by a certified notary public... No biometric screening required yet, but I'd hate to give them any ideas.
For the Kansas application I needed three reference letters total and a signed application. That was it.