The IntRange plugin is a very simple plugin and generates integers in a given range.
It has up to two constructor parameter. The first one is the maximum value and the second one (optional) the minimum. When minimum is not set, the minimum will be 0!

public class Person
  public string Name { get; set; }
  public string LastName { get; set; }
  public int Age { get; set; }
  public DateTime Birthday { get; set; }

public class HelloFiller
  public void FillPerson()
    Filler<Person> pFiller = new Filler<Person>();
      .OnType<int>().Use(new IntRange(20, 79));

    Person filledPerson = pFiller.Create();