Sorry if this question sounds stupid, in the arduino.cc faq page, it says
Using the Arduino core and libraries for the firmware of a commercial product does not require you to release the source code for the firmware. The LGPL does, however, require you to make available object files that allow for the relinking of the firmware against updated versions of the Arduino core and libraries. Any modifications to the core and libraries must be released under the LGPL.
How do you make the object files/where are the object files located using the Arduino IDE?