gistfile1.txt

  # TODO: figure out how to refer to the nat instance when creating
  # the elastic ip
  dynamic!(:nat_instance, 'indigo', :nat_instance_type => ref!(:nat_instance_type), :ssh_key_name => ref!(:ssh_key_name))
  dynamic!(:elastic_ip, 'indigo_nat', :instance => ref!(:indigo_nat_instance))

gistfile2.txt

  mappings.nat_ami_64 do
    set!('us-east-1', :ami => 'ami-184dc970') # amzn-ami-vpc-nat-hvm-2014.09.1.x86_64-gp2
    set!('us-west-1', :ami => 'ami-a98396ec')
    set!('us-west-2', :ami => 'ami-290f4119')
  end

gistfile3.txt

  resources("#{_name}_elastic_ip_association".to_sym) do
    type 'AWS::EC2::EIPAssociation'
    properties do
      #allocation_id attr!("#{_name}_nat_instance_elastic_ip".to_sym, :allocation_id)
      e_i_p ref!("#{_name}_elastic_ip".to_sym) # lol
      instance_id _config[:instance]
    end
  end
  
  becomes...
  
      "IndigoNatElasticIpAssociation": {
      "Type": "AWS::EC2::EIPAssociation",
      "Properties": {
        "EIP": {
          "Ref": "IndigoNatElasticIp"
        },
        "InstanceId": {
          "Ref": "IndigoNatInstance"
        }
      }
    }

Note that "e_i_p" becomes "EIP."  Otherwise, the "Eip" property is unknown.