A couple of new ones which I thought merited mention:
Free book:
==Programming==
http://pythonforengineers.com/python-for-scientists-and-engineers/ [ https://www.reddit.com/r/Python/comments/6bat6d/python_for_scientists_and_engineers_is_now_free/ ]
and new control software for a Pi:
https://github.com/Nikolay-Kha/PyCNC — https://www.reddit.com/r/CNC/comments/6b6g05/pycnc_first_cnc_machine_controller_on_pure_python/