Preventing ActiveRecord save() on an instance

There might be a more idiomatic way to do this, but one way would be to set a virtual attribute and check it in a before_save callback. When you clone the object, set the virtual attribute – maybe something like is_clone to true. Then define a before_save callback for your model class that prevents the save if that attribute is set.

You can use ActiveRecord::Base#readonly!

model = MyModel.find 1
model.readonly!
model.save!

it will raise ActiveRecord::ReadOnlyRecord