I think if you take a thread link and add &page=all
at the end of the number=xxx you'll get everything in one post, and maybe you could hit print then?
For example:
https://www.yenko.net/ubbthreads/ubbt...392&page=1 gets you to the 1st page of the thread
This here brings the whole thread on one page:
https://www.yenko.net/ubbthreads/ubbt...2&page=all
But sometimes I print things out and pictures get truncated. It might be best to pring them to a PDF, since you may be able to configure a different page size so things don't get cut off.
Did I kinda help, or was this obvious already?