diff --git a/core/lib/Drupal/Core/Layout/IconGenerator.php b/core/lib/Drupal/Core/Layout/IconGenerator.php
index dfa0b1b..6b5a2c2 100644
--- a/core/lib/Drupal/Core/Layout/IconGenerator.php
+++ b/core/lib/Drupal/Core/Layout/IconGenerator.php
@@ -3,38 +3,14 @@
 namespace Drupal\Core\Layout;
 
 /**
- * A class that supports generating layout icons based on well-formed config.
- *
- * @internal
- *   The layout system is currently experimental and should only be leveraged by
- *   experimental modules and development releases of contributed modules.
- *   See https://www.drupal.org/core/experimental for more information.
+ * Generates layout icons from well-formed config.
  */
-class IconGenerator {
+class IconGenerator implements IconGeneratorInterface {
 
   /**
-   * Generates a SVG based on a Layout's icon map.
-   *
-   * @param array $icon_map
-   *   A two dimensional array representing the visual output of the layout.
-   * @param int $width
-   *   (optional) The width of the generated SVG. Defaults to 250.
-   * @param int $height
-   *   (optional) The height of the generated SVG. Defaults to 300.
-   * @param string $fill
-   *   (optional) The fill color of regions. Defaults to 'lightgray'.
-   * @param string $stroke
-   *   (optional) The color of region borders. Defaults to 'black'.
-   * @param int $stroke_width
-   *   (optional) The width of region borders. Defaults to 2.
-   * @param int $padding
-   *   (optional) The padding between regions. Any value above 0 is valid.
-   *   Defaults to 5.
-   *
-   * @return array
-   *   A render array representing a SVG icon.
+   * {@inheritdoc}
    */
-  public function generateSvgFromIconMap($icon_map, $width = 250, $height = 300, $fill = 'lightgray', $stroke = 'black', $stroke_width = 2, $padding = 5) {
+  public function generateSvgFromIconMap(array $icon_map, $width = 250, $height = 300, $stroke_width = 1, $padding = 3, $fill = 'lightgray', $stroke = 'black') {
     $build = [
       '#type' => 'html_tag',
       '#tag' => 'svg',
diff --git a/core/lib/Drupal/Core/Layout/IconGeneratorInterface.php b/core/lib/Drupal/Core/Layout/IconGeneratorInterface.php
new file mode 100644
index 0000000..369b33f
--- /dev/null
+++ b/core/lib/Drupal/Core/Layout/IconGeneratorInterface.php
@@ -0,0 +1,52 @@
+<?php
+
+namespace Drupal\Core\Layout;
+
+/**
+ * Provides an interface for generating layout icons from well-formed config.
+ */
+interface IconGeneratorInterface {
+
+  /**
+   * Generates a SVG based on a Layout's icon map.
+   *
+   * @param array $icon_map
+   *   A two dimensional array representing the visual output of the layout.
+   *   For the following shape:
+   *   |------------------------------|
+   *   |                              |
+   *   |             100%             |
+   *   |                              |
+   *   |-------|--------------|-------|
+   *   |       |              |       |
+   *   |  25%  |      50%     |  25%  |
+   *   |       |              |       |
+   *   |-------|--------------|-------|
+   *   |                              |
+   *   |             100%             |
+   *   |                              |
+   *   |------------------------------|
+   *   The corresponding array would be:
+   *   - [top]
+   *   - [first, second, second, third]
+   *   - [bottom].
+   * @param int $width
+   *   (optional) The width of the generated SVG. Defaults to 250.
+   * @param int $height
+   *   (optional) The height of the generated SVG. Defaults to 300.
+   * @param int $stroke_width
+   *   (optional) The width of region borders. Defaults to 2.
+   * @param int $padding
+   *   (optional) The padding between regions. Any value above 0 is valid.
+   *   Defaults to 5.
+   * @param string $fill
+   *   (optional) The fill color of regions. Defaults to 'lightgray'.
+   * @param string $stroke
+   *   (optional) The color of region borders. Defaults to 'black'.
+   *
+   * @return array
+   *   A render array representing a SVG icon.
+   */
+  public function generateSvgFromIconMap(array $icon_map, $width = 250, $height = 300, $stroke_width = 1, $padding = 3, $fill = 'lightgray', $stroke = 'black');
+
+}
diff --git a/core/lib/Drupal/Core/Layout/LayoutDefinition.php b/core/lib/Drupal/Core/Layout/LayoutDefinition.php
index a4c66d6..a2be60b 100644
--- a/core/lib/Drupal/Core/Layout/LayoutDefinition.php
+++ b/core/lib/Drupal/Core/Layout/LayoutDefinition.php
@@ -372,18 +372,40 @@ public function setIconPath($icon) {
   }
 
   /**
+   * Builds a render array for an icon representing the layout.
+   *
+   * @param int $width
+   *   (optional) The width of the icon. Defaults to 250.
+   * @param int $height
+   *   (optional) The height of the icon. Defaults to 300.
+   * @param int $stroke_width
+   *   (optional) If a generated SVG is used, the width of region borders.
+   *   Defaults to 2.
+   * @param int $padding
+   *   (optional) If a generated SVG is used, the padding between regions. Any
+   *   value above 0 is valid. Defaults to 5.
+   * @param string $fill
+   *   (optional) If a generated SVG is used, the fill color of regions.
+   *   Defaults to 'lightgray'.
+   * @param string $stroke
+   *   (optional) If a generated SVG is used, the color of region borders.
+   *   Defaults to 'black'.
+   *
    * @return array
+   *   A render array for the icon.
    */
-  public function getIcon() {
+  public function getIcon($width = 250, $height = 300, $stroke_width = 2, $padding = 5, $fill = 'lightgray', $stroke = 'black') {
     $icon = [];
     if ($icon_path = $this->getIconPath()) {
       $icon = [
         '#theme' => 'image',
         '#uri' => $icon_path,
+        '#width' => $width,
+        '#height' => $height,
       ];
     }
     elseif ($icon_map = $this->get('icon_map')) {
-      $icon = $this->getIconGenerator()->generateSvgFromIconMap($icon_map);
+      $icon = $this->getIconGenerator()->generateSvgFromIconMap($icon_map, $width, $height, $stroke_width, $padding, $fill, $stroke);
     }
     return $icon;
   }
diff --git a/core/modules/layout_discovery/layout_discovery.layouts.yml b/core/modules/layout_discovery/layout_discovery.layouts.yml
index 16ffc63..755a96b 100644
--- a/core/modules/layout_discovery/layout_discovery.layouts.yml
+++ b/core/modules/layout_discovery/layout_discovery.layouts.yml
@@ -39,6 +39,12 @@ layout_twocol_bricks:
   library: layout_discovery/twocol_bricks
   category: 'Columns: 2'
   default_region: middle
+  icon_map:
+    - [top]
+    - [first_above, second_above]
+    - [middle]
+    - [first_below, second_below]
+    - [bottom]
   regions:
     top:
       label: Top
@@ -62,6 +68,10 @@ layout_threecol_25_50_25:
   library: layout_discovery/threecol_25_50_25
   category: 'Columns: 3'
   default_region: second
+  icon_map:
+    - [top]
+    - [first, second, second, third]
+    - [bottom]
   regions:
     top:
       label: Top
@@ -81,6 +91,10 @@ layout_threecol_33_34_33:
   library: layout_discovery/threecol_33_34_33
   category: 'Columns: 3'
   default_region: first
+  icon_map:
+    - [top]
+    - [first, second, third]
+    - [bottom]
   regions:
     top:
       label: Top
diff --git a/core/modules/layout_discovery/layouts/twocol/twocol.png b/core/modules/layout_discovery/layouts/twocol/twocol.png
deleted file mode 100644
index f0a094e..0000000
--- a/core/modules/layout_discovery/layouts/twocol/twocol.png
+++ /dev/null
@@ -1,3 +0,0 @@
-‰PNG
-
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\ No newline at end of file