If you're just trying to visualize your data, have a look at Data::Dumper.

Otherwise, with a few modifications, your code works. 

use strict;
use warnings;

use Data::Dumper;

my %ThreeD = (
              TV => {
                     version3 => {
                                  lead      => "fred",
                                  pal       => "barney",
                              },
                 },
          );

print Dumper( \%ThreeD );

# print the whole thing
foreach my $media ( keys %ThreeD) {
    print "$media @ {";
    for my $media_ver ( keys %{ $ThreeD{$media} } ) {
        print "$media_ver { ";
        for my $leaf_obj ( keys %{ $ThreeD{$media}{$media_ver} } ) {
            print "$leaf_obj=$ThreeD{$media}{$media_ver}{$leaf_obj} ";
        }
    }
    print "}\n";
}
__END__
$VAR1 = { 
          'TV' => { 
                    'version3' => { 
                                    'lead' => 'fred',
                                    'pal' => 'barney'
                                  }
                  }
        };
TV @ {version3 { lead=fred pal=barney }

[download]

Always use strict. It highlighted one of your errors for me. Specifically, you used $media_ver before it was defined. The other problem I found was just that your syntax for accessing the second level down was wrong (it's $ThreeD{$media}{$media_ver}).

In reply to Re: 3D Hash by kyle
in thread 3D Hash by Withnail

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.