Peter Stammbach shows how to create the inside Threads of a bottle cap with modo demonstrating how to get rid of the n-tons that might show up during the modeling process.
how to convert n-gons at the beginning and end of a thread
Peter shows how to build a cap without the use of boolean operations. Complex forms such as a bottle cap always interest me in that they are seemingly simple, yet also technically complex, especially if you are intent on keeping quads all throughout the process.