diff --git a/cameo/zstack.pl b/cameo/zstack.pl
new file mode 100755
index 0000000..e5c1d2e
--- /dev/null
+++ b/cameo/zstack.pl
@@ -0,0 +1,64 @@
+#!/usr/bin/perl
+#
+# zstack.pl - Convert 2.5D paths into a stack with limited Z steps
+#
+# Written 2012 by Werner Almesberger
+# Copyright 2012 Werner Almesberger
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+
+
+sub usage
+{
+	print STDERR "usage: $0 z-start z-maxstep [file ...]\n";
+	exit(1);
+}
+
+
+sub issue
+{
+	local ($z) = @_;
+	my $t;
+
+	#
+	# The order here is a bit arbitrary. We sort to make the outcome
+	# more predictable but it shouldn't really matter.
+	#
+	for my $c (sort { $b <=> $a } grep { $_ <= $z } keys %z) {
+		($t = $z{$c}) =~ s/\s+-?\d+(\.\d*)?$/ $z/mg;
+		print $t;
+	}
+}
+
+
+$z0 = shift @ARGV;
+$zs = shift @ARGV;
+
+$z0 =~ s/mm$//;
+$zs =~ s/mm$//;
+
+&usage unless $zs > 0;
+
+while (<>) {
+	if (/^\s*$/) {
+		$z{$z} .= "$s\n";
+		undef $s;
+	}
+	$z = $3 if /^-?\d+(\.\d*)?\s+-?\d+(\.\d*)?\s+(-?\d+(\.\d*)?)/;
+	$s .= $_;
+}
+$z{$z} .= "$s\n";
+
+$z = $z0;
+for $c (sort { $b <=> $a } keys %z) {
+	while ($z > $c+$zs) {
+		$z -= $zs;
+		&issue($z);
+	}
+	$z = $c;
+	&issue($z);
+}