diff --git a/src/main/kotlin/com/martianwabbit/hpglWriter.kt b/src/main/kotlin/com/martianwabbit/hpglWriter.kt
index c91496e..d89576b 100644
--- a/src/main/kotlin/com/martianwabbit/hpglWriter.kt
+++ b/src/main/kotlin/com/martianwabbit/hpglWriter.kt
@@ -49,8 +49,7 @@ class HPGL(
                                     hpgl.cmd("PU", segment.start) // Go to shape start
                                     hpgl.cmd("PD", segment.end)
                                 } else {
-                                    hpgl.cmd("PD", segment.start) // PD coordinates for all other segments
-                                    hpgl.cmd("PD", segment.end) // PD coordinates for all other segments
+                                    hpgl.cmd("PD", segment.start, segment.end) // PD coordinates for all other segments
                                 }
                             }
 
@@ -58,13 +57,8 @@ class HPGL(
                         }
                     }
 
-                    is SelectPen -> {
-                        hpgl.cmd("SP", this.penNumber)
-                    }
-
-                    is VelocitySelect -> {
-                        hpgl.cmd("VS", this.velocity)
-                    }
+                    is SelectPen -> hpgl.cmd("SP", this.penNumber)
+                    is VelocitySelect -> hpgl.cmd("VS", this.velocity)
                 }
             }
         }
@@ -89,29 +83,31 @@ private fun CompositionNode.traverse(cb: CompositionNode.(stage: Stage) -> Unit)
     this.cb(Stage.After)
 }
 
+private val Vector2.coords: String
+    get() {
+        return "$x,$y"
+    }
+
+
 // HPGL Custom Instructions
-class SelectPen(val penNumber: Int) : GroupNode()
+private class SelectPen(val penNumber: Int) : GroupNode()
 
 fun CompositionDrawer.selectPen(pen: Int) {
     require(pen >= 0) { "The pen can only be 0 or greater." }
     this.root.children.add(SelectPen(pen))
 }
 
-class VelocitySelect(val velocity: Double) : GroupNode()
+private class VelocitySelect(val velocity: Double) : GroupNode()
 
 fun CompositionDrawer.velocitySelect(velocity: Double) {
     require(velocity in 0.0..127.9999) { "Invalid velocity value. The velocity should be a value between 0 and 127.9999" }
     this.root.children.add(VelocitySelect(velocity))
 }
 
+// StringBuilder Extensions
 private fun StringBuilder.cmd(cmd: String) = this.appendln("$cmd;")
 private fun StringBuilder.cmd(cmd: String, i: Int) = this.appendln("$cmd${i};")
 private fun StringBuilder.cmd(cmd: String, i: Double) = this.appendln("$cmd${i};")
 private fun StringBuilder.cmd(cmd: String, vararg vectors: Vector2) {
     this.appendln(vectors.joinToString(prefix = cmd, postfix = ";") { it.coords })
 }
-
-private val Vector2.coords: String
-    get() {
-        return "$x,$y"
-    }