diff --git a/cameo/README b/cameo/README
index 724cdb2..0af9613 100644
--- a/cameo/README
+++ b/cameo/README
@@ -170,6 +170,9 @@ what "offset" does.
 The overlap is the distance by which the areas cleared by parallel paths
 should overlap.
 
+If the current paths have different Z coordinates, each level is
+processed separately.
+
 
 Drill/mill conversion:
 
diff --git a/cameo/area.c b/cameo/area.c
index 3d2ff19..1b23429 100644
--- a/cameo/area.c
+++ b/cameo/area.c
@@ -16,7 +16,6 @@
  * outlines without cutting into anything it's not supposed to.
  */
 
-#include <stdio.h>
 #include <stddef.h>
 #include <math.h>
 #include <assert.h>
@@ -209,18 +208,20 @@ static int hit_path(double fx, double fy, double tx, double ty,
 
 
 static const struct path **subordinates(const struct path *paths,
-    const struct path *path)
+    const struct path *path, double z)
 {
 	const struct path **sub, **w, **a, **b;;
 	const struct path *p;
 	int n = 0;
 
 	for (p = paths; p; p = p->next)
-		n++;
+		if (p->first && p->first->z == z)
+			n++;
 	sub = alloc_size(sizeof(struct path *)*n);
 	w = sub;
 	for (p = paths; p; p = p->next)
-		if (p != path && is_inside(p, path) && !is_inside(path, p))
+		if (p != path && p->first && p->first->z == z &&
+		    is_inside(p, path) && !is_inside(path, p))
 			*w++ = p;
 	*w = NULL;
 	for (a = sub; a != w; a++)
@@ -283,7 +284,7 @@ static void add_outline(const struct path *path, int inside, struct path **res)
 
 
 static void fill_path(const struct path *paths, const struct path *path,
-    double r_tool, double overlap, struct path **res)
+    double z, double r_tool, double overlap, struct path **res)
 {
 	const struct path **sub, **s;
 	const struct path **sub2, **s2;
@@ -292,7 +293,7 @@ static void fill_path(const struct path *paths, const struct path *path,
 
 	if (!bbox(path, &xa, &ya, &xb, &yb))
 		return;
-	sub = subordinates(paths, path);
+	sub = subordinates(paths, path, z);
 	xa += r_tool;
 	ya += 3*r_tool-overlap;
 	xb -= r_tool;
@@ -302,9 +303,9 @@ static void fill_path(const struct path *paths, const struct path *path,
 		do_line(path, sub, xa, xb, ya+(yb-ya)*((double) i/n),
 		    r_tool, overlap, res);
 	for (s = sub; *s; s++) {
-		sub2 = subordinates(paths, *s);
+		sub2 = subordinates(paths, *s, z);
 		for (s2 = sub2; *s2; s2++)
-			fill_path(paths, *s2, r_tool, overlap, res);
+			fill_path(paths, *s2, z, r_tool, overlap, res);
 		free(sub2);
 		add_outline(*s, 0, res);
 	}
@@ -313,12 +314,36 @@ static void fill_path(const struct path *paths, const struct path *path,
 }
 
 
-struct path *area(const struct path *path, double overlap)
+struct path *area(const struct path *paths, double overlap)
 {
 	struct path *res = NULL;
+	double z = HUGE_VAL, best_x, x;
+	const struct path *path, *best;
+	const struct point *p;
 
-	if (!path)
+	if (!paths)
 		return NULL;
-	fill_path(path, path_find_leftmost(path), path->r_tool, overlap, &res);
-	return res;
+	while (1) {
+		best = NULL;
+		best_x = HUGE_VAL;
+		for (path = paths; path; path = path->next) {
+			if (!path->first)
+				continue;
+			if (path->first->z >= z)
+				continue;
+			x = HUGE_VAL;
+			for (p = path->first; p; p = p->next)
+				if (p->x < x)
+					x = p->x;
+			if (best && best->first->z >= path->first->z &&
+			    x >= best_x)
+				continue;
+			best = path;
+			best_x = x;
+		}
+		if (!best)
+			return res;
+		z = best->first->z;
+		fill_path(paths, best, z, best->r_tool, overlap, &res);
+	}
 }
diff --git a/cameo/area.h b/cameo/area.h
index d68de2f..9915a15 100644
--- a/cameo/area.h
+++ b/cameo/area.h
@@ -18,6 +18,6 @@
 #include "path.h"
 
 
-struct path *area(const struct path *path, double overlap);
+struct path *area(const struct path *paths, double overlap);
 
 #endif /* !AREA_H */