In some cases Netshell/Paypal throws error "Class Paypal does not exist". In my case on ubuntu/php7/nginx (on windows with apache is ok). So here is simple workaround
$paypal = new \Netshell\Paypal\Paypal;
$this->_apiContext = $paypal->ApiContext(
config('services.paypal.client_id'),
config('services.paypal.secret'));
$this->_apiContext->setConfig([
'mode' => 'sandbox',
'service.EndPoint' => 'https://api.sandbox.paypal.com',
'http.ConnectionTimeOut' => 30,
'log.LogEnabled' => true,
'log.FileName' => storage_path('logs/paypal.log'),
'log.LogLevel' => 'FINE'
]);