There are a lot of challenges with this problem and I’ve been working on this for a while without much progress..

I may have enough ideas on how to solve the numerous issues so I am starting to make the first proof of concept experiments.

This is subject to change but I’ve got a wheel that can roll back and forth in a grove to fold paper. The paper will be folded nearly 90 degrees if this works. I will retracted the paper then rolled over again to press the crease to a compete fold. I’m going to have to build a working model just to prove and refine this concept.

I have another system in mind for the folding. I am able to create a fold using two pieces of extruded aluminum angle. The fold comes out to about 70 degrees and is very clean. The difficulty here is it needs a fair amount of force. Not sure if that’s going to be easier or harder than the roller. I’ll probably draw both these up and then decide which one to try first.

Also I’m considering a track with rollers like a real paper handling and folding machine. I figure that’s the hardest so I’ve got that as backup. But I’m still thinking about it. I don’t have any rollers on hand. I guess I can make some out of o-rings.

The paper handling will be a movable servo that can rotate and move the paper. A second servo will raise and lower it so it can release and grab the paper.

Related

https://www.youtube.com/watch?v=NWTvpPg2Wtc