Welcome to FindNerd. Today we are going to discuss the client token generation on braintree. You can create a unique client tokens for different process. Please have a look.

public function getBraintreeClientToken($customer_id = null)
{
        if (!empty($customer_id) && is_int($customer_id))
            $client_token = Braintree_ClientToken::generate(array("customerId"=>$customer_id));
        else
            $client_token = Braintree_ClientToken::generate();

        if(isset($client_token)){
            echo json_encode(array('status' => 'success','message' => 'Token generated','client_token'=> $client_token)); die; 
        }else{
            echo json_encode(array('status' => 'fail','message' => 'Token not generated.please try again!')); die;
                }
}

We created a function getBraintreeClientToken which is taking customer id as an argument. You can create token for specific customer or same token for all.