Registries are pretty cool, I guess

src/main/java/com/dfsek/terra/biome/PaletteHolder.java

@@ -1,10 +0,0 @@
-package com.dfsek.terra.biome;
-
-import org.bukkit.block.data.BlockData;
-import org.polydev.gaea.world.palette.Palette;
-
-public class PaletteHolder {
-    public Palette<BlockData> getPalette(int y) {
-        return null; // TODO: implementation
-    }
-}

src/main/java/com/dfsek/terra/biome/palette/PaletteHolder.java

@@ -0,0 +1,16 @@
+package com.dfsek.terra.biome.palette;
+
+import org.bukkit.block.data.BlockData;
+import org.polydev.gaea.world.palette.Palette;
+
+public class PaletteHolder {
+    private final Palette<BlockData>[] palettes;
+
+    protected PaletteHolder(Palette<BlockData>[] palettes) {
+        this.palettes = palettes;
+    }
+
+    public Palette<BlockData> getPalette(int y) {
+        return palettes[y];
+    }
+}

src/main/java/com/dfsek/terra/biome/palette/PaletteHolderBuilder.java

@@ -0,0 +1,33 @@
+package com.dfsek.terra.biome.palette;
+
+import com.dfsek.terra.util.DataUtil;
+import org.bukkit.block.data.BlockData;
+import org.polydev.gaea.world.palette.Palette;
+
+import java.util.Map;
+import java.util.TreeMap;
+
+public class PaletteHolderBuilder {
+    private final TreeMap<Integer, Palette<BlockData>> paletteMap = new TreeMap<>();
+
+    public PaletteHolderBuilder add(int y, Palette<BlockData> palette) {
+        paletteMap.put(y, palette);
+        return this;
+    }
+
+    @SuppressWarnings("unchecked")
+    public PaletteHolder build() {
+        Palette<BlockData>[] palettes = new Palette[paletteMap.lastKey() + 1];
+        for(int y = 0; y <= paletteMap.lastKey(); y++) {
+            Palette<BlockData> d = DataUtil.BLANK_PALETTE;
+            for(Map.Entry<Integer, Palette<BlockData>> e : paletteMap.entrySet()) {
+                if(e.getKey() >= y) {
+                    d = e.getValue();
+                    break;
+                }
+            }
+            palettes[y] = d;
+        }
+        return new PaletteHolder(palettes);
+    }
+}