Form

symfony console make:form ProductType Product      # bound to an entity
symfony console make:form ContactType              # bound to nothing

Both the form class and the class it binds to are arguments, so the maker asks nothing when you pass them. Install it first if it is missing: symfony composer require --dev symfony/maker-bundle.

Where things belong

Validation constraints go on the object, not on the form fields. A constraint attached to a field only exists inside that one form; on the entity or DTO it applies everywhere the object is used.

Buttons go in the template, not in the form class. A form used for both creating and editing needs "Add new" in one place and "Save changes" in the other — the class should not know which. Styling belongs in the template too. The exception is a form with several submit buttons, where the controller has to tell them apart; define those in the controller.

One action renders and processes. Rendering and handling a submission are near-identical in a controller, so splitting them across two actions duplicates the setup for nothing:

$form = $this->createForm(ProductType::class, $product);
$form->handleRequest($request);

if ($form->isSubmitted() && $form->isValid()) {
    // persist, then redirect
}

return $this->render('product/edit.html.twig', ['form' => $form]);

What the maker leaves you

A FormType with a buildForm() and a configureOptions(). Keep the data_class it set when the form is bound. Field types are guessed from the mapping and are worth revisiting — an entity property is not always the widget a user should see.