How to allow unique Laravel Facade instances when using Builder pattern?

Im using the Builder pattern but get data mixup between calls. I want a fresh instance on each static call to my facade. Example:

Underlying class

<?php

namespace Me\Package;

class PHPFile
{
    public function set($key, $value) {
        $this->$key = $value;
        return $this;
    }

    public function get($key) {
        return isset($this->$key) ? $this->key : 'NO_SUCH_KEY';
    }

    public function sum()
    {
        // example of an "ending" method
    }
}

The facade

<?php

namespace Me\Package\Facades;

use Illuminate\Support\Facades\Facade;

class PHPFile extends Facade {
   protected static function getFacadeAccessor() { return 'PHPFile'; }
}

Serviceprovider

use Me\Package\PHPFile;

public function register()
{
    App::bind('PHPFile',function() {
        return new PHPFile;
    });
}

Test

print PHPFile::set('first', 10)->set('second', 20)->sum();
// 30
print PHPFile::get('first');
// 10 !!!

Since facades keep the same instance the second test row will print 10. I want 'NO_SUCH_KEY' here - a new instance after each static call. How can I do that? I tried making the facade return a minimal "factory", simply a constructor returning a new PHPFile instance but did not succeed that way. I also read I should call a new static in the "ending"-methods (sum/get) but not sure how to do that and keep the accumulated data.

Add a factory

This factory will intercept any call with magic __call method, then dispatch it to a fresh PHPFile (My Builder class)

<?php

namespace Me\Package\Factories;

use Me\Package\PHPFile;

class PHPFileFactory
{
    public function __call($method, $args)
    {
        return (new PHPFile)->$method(...$args);
    }    
}

Bind the factory in the serviceprovider

App::bind('PHPFile',function() {
    return new PHPFileFactory;
});

Thanks to @apokryfos who pointed out I needed to return something else - not the Builder itself but another class.