I had fun with this:

#!/usr/bin/perl

use warnings;
use strict;
use Data::Dumper;

my @flat = ( 1 .. 9 ) x 3;

sub make_matrix
{
    my ($dims_ref, $flat_ref) = @_;

    my @dims        = @$dims_ref;
    my $current_dim = shift @dims;
    my $result      = [];

    return [ splice @$flat_ref, 0, $current_dim ] unless @dims;

    for ( 1 .. $current_dim ) {
        push @$result, make_matrix( \@dims, $flat_ref );
    }

    return $result;
}

# @flat is spliced to itty bits :(
my $matrix = make_matrix( [ 3, 3, 3 ], \@flat );

print Dumper($matrix);
printf "%d x %d x %d\n",
    scalar @$matrix, scalar @{$matrix->[0]}, scalar @{$matrix->[0][0]}
+;
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