e.g. if i hear of a cool idea for a new and/or improved gadget, i
can build one myself and use it whenever i like.
In the US, you can be sued for patent infringement for doing that. I
am not certain that it is so in all countries. Do you know with
certainty that some countries make an exception for that kind of use?
Either way, the program can't be considered free software in the
countries where there are patents.