diff --git a/plot-3d-slack.py b/plot-3d-slack.py
index bad2dc9..83226fa 100755
--- a/plot-3d-slack.py
+++ b/plot-3d-slack.py
@@ -3,6 +3,7 @@
 import numpy as np
 from scipy.interpolate import griddata
 import sys
+import yaml
 
 
 def load_data(filename):
@@ -11,20 +12,34 @@ def load_data(filename):
     slack = []
 
     with open(filename, "r") as file:
-        for line in file:
-            parts = line.split()
-            if len(parts) == 5:
-                s = float(parts[2])
-                slack.append(s * pow(10, 12))
-                x.append(float(parts[3]))
-                y.append(float(parts[4]))
+        data = yaml.load(file, Loader=yaml.FullLoader)
 
-    return np.array(x), np.array(y), np.array(slack)
+    for line in data["stats"]:
+        parts = line.split()
+        if len(parts) == 5:
+            s = float(parts[2])
+            slack.append(s * pow(10, 12))
+            x.append(float(parts[3]))
+            y.append(float(parts[4]))
 
+    macros = {}
 
-def plot_3d(x, y, z):
+    for line in data["masters"]:
+        parts = line.split()
+        if len(parts) == 5:
+            macros[parts[0]] = {
+                "minx": float(parts[1]),
+                "miny": float(parts[2]),
+                "maxx": float(parts[3]),
+                "maxy": float(parts[4]),
+            }
+
+    return np.array(x), np.array(y), np.array(slack), macros
+
+
+def plot_3d(x, y, z, macros):
     # Create grid data for surface plot
-    grid_x, grid_y = np.mgrid[0: 2000: 100j, 0: 2000: 100j]
+    grid_x, grid_y = np.mgrid[0:2000:100j, 0:2000:100j]
     grid_z = griddata((x, y), z, (grid_x, grid_y), method="linear")
 
     fig = plt.figure()
@@ -36,10 +51,32 @@ def plot_3d(x, y, z):
     ax.set_zlabel("Skew")
     fig.colorbar(surf, ax=ax, shrink=0.5, aspect=5)
 
+    for macro in macros:
+        minx = macros[macro]["minx"]
+        miny = macros[macro]["miny"]
+        maxx = macros[macro]["maxx"]
+        maxy = macros[macro]["maxy"]
+
+        # Plot a solid rectangle
+        ax.bar3d(minx, miny, 0, maxx - minx, maxy - miny, 50, color="red", alpha=0.5)
+
+        # # Add title text on the flat surface of the box
+        # ax.text(
+        #     (minx + maxx) / 2,  # x-coordinate of the text
+        #     (miny + maxy) / 2,  # y-coordinate of the text
+        #     0.5,                # z-coordinate of the text (middle of the box height)
+        #     macro,              # text to display
+        #     color='black',      # text color
+        #     ha='center',        # horizontal alignment
+        #     va='center',        # vertical alignment
+        #     fontsize=12,        # font size
+        #     bbox=dict(facecolor='white', alpha=0.5, edgecolor='none')  # background box
+        # )
+
     plt.show()
 
 
 if __name__ == "__main__":
     filename = sys.argv[1]
-    x, y, z = load_data(filename)
-    plot_3d(x, y, z)
+    x, y, z, macros = load_data(filename)
+    plot_3d(x, y, z, macros)
diff --git a/slack-positions.tcl b/slack-positions.tcl
index 025426a..6d11eee 100644
--- a/slack-positions.tcl
+++ b/slack-positions.tcl
@@ -1,3 +1,5 @@
+# To test from ~/OpenROAD-flow-scripts, run:
+# make RUN_SCRIPT=~/megaboom/slack-positions.tcl ODB_FILE=results/nangate45/gcd/base/4_cts.odb run OUTPUT=xxx.txt
 source $::env(SCRIPTS_DIR)/open.tcl
 
 set paths [find_timing_paths -path_group reg2reg -sort_by_slack -group_count 1000000]
@@ -6,6 +8,7 @@ set db [::ord::get_db]
 set block [[$db getChip] getBlock]
 
 set fp [open $::env(OUTPUT) w]
+puts $fp "stats:"
 foreach path $paths {
   set endpoint [get_property $path endpoint]
   set instance [sta::sta_to_db_inst [$endpoint instance]]
@@ -23,6 +26,15 @@ foreach path $paths {
   set slack [get_property $path slack]
   set skew [$path clk_skew]
   set bbox [$obj getBBox]
-  puts $fp "$name $slack $skew [ord::dbu_to_microns [$bbox xMin]] [ord::dbu_to_microns [$bbox yMin]]"
+  puts $fp "  - $name $slack $skew [ord::dbu_to_microns [$bbox xMin]] [ord::dbu_to_microns [$bbox yMin]]"
 }
+
+puts $fp "masters:"
+foreach master [$block getInsts] {
+  if {[$master isBlock]} {
+    set bbox [$master getBBox]
+    puts $fp "  - [$master getName] [ord::dbu_to_microns [$bbox xMin]] [ord::dbu_to_microns [$bbox yMin]] [ord::dbu_to_microns [$bbox xMax]] [ord::dbu_to_microns [$bbox yMax]]"
+  }
+}
+
 close $fp