diff --git a/chapter-qkd/chapter.tex b/chapter-qkd/chapter.tex
index 8673dbd..4c2c3f1 100644
--- a/chapter-qkd/chapter.tex
+++ b/chapter-qkd/chapter.tex
@@ -154,6 +154,10 @@
 \newcommand{\camerareadygraphics}{\ifdefined\thesispreviewmode Camera-ready graphics. \fi}
 \newcommand{\scaledgraphics}[1]{\ifdefined\thesispreviewmode scaled-#1\else#1\fi}
 
+\newcommand{\imgsource}[4]{\scriptsize%
+    Image source: #1, #2 (\underline{\href{#4}{link}}). %
+    Licensed #3.}
+
 \hyphenation{a-me-na-ble}
 
 \begin{document}
@@ -682,10 +686,26 @@ interface layer between the two meshes can be made more complex. By introducing
 into the inter-mesh space from both meshes, creating a labyrinth-like structure that requires structural support and
 cables to pass in a series of \qty{90}{\degree} bends.
 
-Designing this type of labyrinth mesh is similar to the design of the shape of the jamb of a safe door or of a high-end
-european-style apartment door, where the objective is to prevent would-be burglars from inserting opening tools through
-the space between the closed door and its jamb and attacking the door's interior handle. \todo{some pics would be nice
-here}
+\begin{figure}[h!]
+    \centering
+    \includegraphics[width=.7\textwidth]{\scaledgraphics{wikimedia_Four_Corners_Bank_Vault_cropped.jpg}}
+    \caption[Photo of a bank vault door]{\draftgraphics Photo of a bank vault door at the Four Corners building in
+    Bowling Green, Ohio, USA. The interface between the door and its frame is stepped all around to discourage would-be
+    intruders from inserting any sort of tool through the small gap around the closed door. In this instance, because
+    the door's sill is stepped, too, a small ramp has been placed over the sill so that people going in and out of the
+    open door don't stumble over the steps.\\
+    \imgsource{Wikimedia Commons user Mbrickn}{2019}{CC-BY-SA}{https://commons.wikimedia.org/wiki/File:Four_Corners_Bank_Vault.jpg}
+    }
+    \label{qkd_fig_vault_door}
+\end{figure}
+
+Designing this type of labyrinth mesh is similar to the design of the shape of the jamb of a safe door such as the one
+shown in Figure\ \ref{qkd_fig_vault_door}, or of a high-end European-style apartment door. In these, the objective is to
+prevent would-be burglars from inserting opening tools through the space between the closed door and its jamb and
+attacking the door's interior handle or locking mechanism, not unlike an IHSM's defense against electrical or
+electromagnetic probes. The one difference between these doors and what we can do in IHSMs is that these doors are
+limited to outwards-facing steps because they must be opened and closed. In IHSM labyrinth meshes, we can use both
+outwards-facing and inwards-facing steps.
 
 \subsection{Offset labyrinth meshes}
 
diff --git a/chapter-qkd/figures/render_exp_1.png.latex_meta b/chapter-qkd/figures/render_exp_1.png.latex_meta
index 2f5a7d0..0efc988 100644
--- a/chapter-qkd/figures/render_exp_1.png.latex_meta
+++ b/chapter-qkd/figures/render_exp_1.png.latex_meta
@@ -1,5 +1,5 @@
 \def\resourcestate{\draftgraphics}
-\def\resourcescale{scaled down for preview}
+\def\resourcescale{}
 \def\resourceurl{https://git.jaseg.de/ihsm-secondary-mesh.git/plain/render\_exp\_1.png?h=3a7edbd1127cacc8f4c90376595b894105f3d479}
 \def\resourcerev{3a7edbd}
 \def\resourcerepo{ihsm-secondary-mesh.git}
diff --git a/chapter-qkd/figures/render_exp_2.png.latex_meta b/chapter-qkd/figures/render_exp_2.png.latex_meta
index a96816e..baa07ec 100644
--- a/chapter-qkd/figures/render_exp_2.png.latex_meta
+++ b/chapter-qkd/figures/render_exp_2.png.latex_meta
@@ -1,5 +1,5 @@
 \def\resourcestate{\draftgraphics}
-\def\resourcescale{scaled down for preview}
+\def\resourcescale{}
 \def\resourceurl{https://git.jaseg.de/ihsm-secondary-mesh.git/plain/render\_exp\_2.png?h=3a7edbd1127cacc8f4c90376595b894105f3d479}
 \def\resourcerev{3a7edbd}
 \def\resourcerepo{ihsm-secondary-mesh.git}
diff --git a/chapter-qkd/figures/render_side_1.png.latex_meta b/chapter-qkd/figures/render_side_1.png.latex_meta
index 9bd4584..e8f54a9 100644
--- a/chapter-qkd/figures/render_side_1.png.latex_meta
+++ b/chapter-qkd/figures/render_side_1.png.latex_meta
@@ -1,5 +1,5 @@
 \def\resourcestate{\draftgraphics}
-\def\resourcescale{scaled down for preview}
+\def\resourcescale{}
 \def\resourceurl{https://git.jaseg.de/ihsm-secondary-mesh.git/plain/render\_side\_1.png?h=3a7edbd1127cacc8f4c90376595b894105f3d479}
 \def\resourcerev{3a7edbd}
 \def\resourcerepo{ihsm-secondary-mesh.git}
diff --git a/chapter-qkd/figures/render_side_2.png.latex_meta b/chapter-qkd/figures/render_side_2.png.latex_meta
index 5569c3d..6ab80be 100644
--- a/chapter-qkd/figures/render_side_2.png.latex_meta
+++ b/chapter-qkd/figures/render_side_2.png.latex_meta
@@ -1,5 +1,5 @@
 \def\resourcestate{\draftgraphics}
-\def\resourcescale{scaled down for preview}
+\def\resourcescale{}
 \def\resourceurl{https://git.jaseg.de/ihsm-secondary-mesh.git/plain/render\_side\_2.png?h=3a7edbd1127cacc8f4c90376595b894105f3d479}
 \def\resourcerev{3a7edbd}
 \def\resourcerepo{ihsm-secondary-mesh.git}
diff --git a/chapter-qkd/figures/scaled-wikimedia_Four_Corners_Bank_Vault_cropped.jpg b/chapter-qkd/figures/scaled-wikimedia_Four_Corners_Bank_Vault_cropped.jpg
new file mode 100644
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Binary files /dev/null and b/chapter-qkd/figures/scaled-wikimedia_Four_Corners_Bank_Vault_cropped.jpg differ
diff --git a/chapter-qkd/figures/wikimedia_Four_Corners_Bank_Vault_cropped.jpg b/chapter-qkd/figures/wikimedia_Four_Corners_Bank_Vault_cropped.jpg
new file mode 100644
index 0000000..f1f9e76
Binary files /dev/null and b/chapter-qkd/figures/wikimedia_Four_Corners_Bank_Vault_cropped.jpg differ