Convention Bookmobile

[Bryant]

The Internet Bookmobile is a mobile printing and binding station that travels around printing public domain books in an effort to raise the awareness of the value of the public domain. You can put a station like this together for about 3K, maybe less.

So here's my question. If I were to put together a station like this and use it to print off copies of free RPGs at conventions, what should I worry about? What are important considerations?

Current assumptions:

[*]I don't charge anything. (Can I take donations?)
[*]I don't print out anything that doesn't explicitly give permission for printing or duplication.
[*]I don't print out anything that is, in any form, on sale at the con.
[*]I don't print out commercial PDFs that someone's bought elsewhere and wants me to print out.
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(Hopefully this is the right forum; I thought it was more appropriate than Publishing, since I'm not talking about printing my own stuff. Please correct me if I'm wrong.)