I am using linen (because I had some) and waxed the thread with beeswax, but have just been using DAP weldwood contact cement for the glue (a bunch of places recommended it as easy for beginners and I already had some), I don't think its exactly acid "free" but perhaps a better than some alternatives. The paper is high bond (and high cotton content) paper aka "resume paper", mostly because I prefer writing on it, and have a couple of reams stashed in the office. Sacrificing 50 sheets for an experiment was within my risk envelope.
I was actually pretty sure that the whole project was going to be an unmitigated disaster and was half prepared to write it off to experience, but so far its been only a mitigated disaster. If it continues on as well as its been going so far I'll have to give it another go with better materials and perhaps improve the tooling a smidge (the "not at all a book press" isn't as convenient as a primitive "almost a real book press" would be).
I do have a couple of other things that I'd like to print and bind if this works out so am definitely interested in using better quality materials if I end up doing that.
I was actually considering using hot hide glue for the second attempt, although I haven't really tried using it for anything quite like this before... I figured if I was going traditional.. might as well go traditional I'm not quite sure what to used for the boards in that case though, I don't think single ply would be stable enough? and I'm not quite convinced of my ability to make a thin enough three ply from scratch (although might take a shot at it because the worst that happens is it doesn't work..).
If you have other beginner resources or suggestions I'd be quite happy to hear about them, like I said ... I really have no idea what I'm doing here other than reading a couple of online articles but figured it wasn't a super expensive experiment to try. So far its been a fun project. A+ would recommend attempting.
Love thy neighbor, yet pull down not thy hedge.