I need to hand over a variable from one controller to another (Laravel 5.4)

I need to hand over a Variable ($id) from my "KundenController" to my "ServerController" to link the id of "kunden" to "kunden_id" in my server colum.

Could you help me with that please? im totally stuck

 public function store() //KundenController
{
    $this->validate(request(), [
        'name'=>'required',
        'RAM'=>'required',
        'CPUAnzahl'=>'required',
        'CPUBezeichnung'=>'required',
        'Festplatte1'=>'required'

    ]);
    $server = new Server;
    $kunden = new Kunden;

    $server->name = request('name');
    $server->RAM = request('RAM');
    $server->CPUAnzahl = request('CPUAnzahl');
    $server->CPUBezeichnung = request('CPUBezeichnung');
    $server->Festplatte1 = request('Festplatte1');

    $server->save();

    return redirect('/server/index');
}

 public function store() //ServerController
{
    $this->validate(request(), [
        'name'=>'required',
        'RAM'=>'required',
        'CPUAnzahl'=>'required',
        'CPUBezeichnung'=>'required',
        'Festplatte1'=>'required'

    ]);
    $server = new Server;
    $kunden = new Kunden;

    $server->name = request('name');
    $server->RAM = request('RAM');
    $server->CPUAnzahl = request('CPUAnzahl');
    $server->CPUBezeichnung = request('CPUBezeichnung');
    $server->Festplatte1 = request('Festplatte1');

    $server->save();

    return redirect('/server/index');
}

so i need to get smth like $server->KundenID = request($kunden->id); but thats not working. First time working with Laravel in PHP it would be kinda simple

via n1ghty