use strict;
use Data::Dumper;

my @firstArray = ( "item1", "item2", "item3" );

my $n = @firstArray;
my @results;

for my $i (1..2**$n-1) {
	my @selection;
	for my $j (0..$n-1) {
		if ($i & 2**$j) {
			push @selection, $firstArray[$j];
		}
	}
	push @results, \@selection;
}

print Dumper(\@results);