factory_with_callbacks.rb

# No Boom, it was creating the handle first... cause app Boom
# This does however, as you say, "Boom"

Factory.define :product do |p|
  p.product_handles do |p|
    [Factory.build(:product_handle)]
  end
end

# Only issue here is that the product has knowledge of the handle... knowledge it need not have.
# (I had to add has_many : product_handles to the Product).
# This could however be for the best.