It's very easy to implement using recursion.

my @list;
$list[0]=[1,2,6];
$list[1]=[4,5];
$list[2]=[7,3];

sub combin
{
    @_ or return [];
    my $l = shift;
    map
    {
        my $n = $_;
        map { [ $n, @$_ ] } combin(@_)
    }
    @$l
}

my @comb = combin(@list);

print "@$_\n" for @comb;
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Similar to how I did it another time.

And the functionality is available in a module, Set::CrossProduct.