add_filter( 'upload_mimes', 'upload_allow_types' );
function upload_allow_types( $mimes ) {
$mimes['dwg'] = 'image/vnd.dwg';
$mimes['fbx'] = 'application/octet-stream';
$mimes['max'] = 'application/octet-stream';
$mimes['zip'] = 'application/zip';
return $mimes;
}