So my wild guess was actually pretty close to the mark. You don't need Moose for a has-a relationship, a simple array or hash is essentially that. You are back at the container of RoboPart derived objects I mentioned above. Your Robo object then is just a container that knows how to send messages between the different parts and tosses out the odd message of its own. Consider:

use strict;
use warnings;

package RoboPart;

sub new {
  my ($class, %options) = @_;
  
  return bless \%options, $class;
}

sub dispatch {
  my ($self, $verb, @params) = @_;
  my $handler = $self->can($verb);
  
  die ref $self . " can't $verb\n" if !defined $handler;
  return $handler->($self, @params);
}

sub does {
  my ($self, $verb) = @_;

  return $self->can($verb);
}


package RoboArm;
use parent -norequire, 'RoboPart';

sub pick {
  my ($self, $target) = @_;
  
  print "I am grabbing $target\n";
} 

package RoboFeet;
use parent -norequire, 'RoboPart';

sub walk { 
    my ($self) = shift;  
    my ($x, $y) = @{$self->{Position}} ;
    
    if ( $x > 10 || $y > 10  ) {
        print "Out of boundary. I stop walk\n";
    } else {
         print "I start walk from pos $x $y\n";
    }
}

package Robo;

sub new {
  my ($class) = @_;
  
  return bless {
    Arm => RoboArm->new(),
    Feet => RoboFeet->new(Position => [11, 0]),
    }, $class;    
}
 
sub send {
  my ($self, $verb, @params) = @_;
  
  for my $part (values %$self) {
    $part->dispatch($verb, @params) if $part->does($verb);
  }
}

package main;
 
my $robo = Robo->new();
$robo->send("pick", "Apple");
$robo->send("walk");
[download]

Prints:

I am grabbing Apple
Out of boundary. I stop walk
[download]