[TxMt] permanently removing build files from a project

[Chris Fonnesbecck]

Is there a way of permanently excluding build directories from a project? I have
a Python project that I develop using TextMate, from which I have to repeatedly
delete references to the build directory. After deleting references, of course,
the very next time I build the project, TextMate sees new files and adds them
back into the project.

Any help here most appreciated.