To cut a pickup cavity, a template is used in any case to make a smooth and well fitted space for the pickup. Excisting spaces can be filled up with wood and cut out with a router to adjust the instrument for a different type of pickup if needed.
The standard single coil neck pickup of this telecaster will be replaced by a Seymour Duncan Seth Lover humbucker. The neck is released from the body, to have more space at the neck position. All old parts are removed.
With a router and a template, the cavity is cut for the new and bigger pickup.
The new pickup fits nicely in the body. The pickup fits just deep enough in the body as necessary, so as less as possible wood is removed from the body.
The pickguard is adjusted and the humbucker is mounted. The pickup floats on two bolts and can be adjusted to the right height.
The telecaster after the modification.