diff --git a/lesson_16/objects/objects_app/src/main/java/com/codedifferently/lesson16/strengthmachine/MachineInUseException.java b/lesson_16/objects/objects_app/src/main/java/com/codedifferently/lesson16/strengthmachine/MachineInUseException.java
new file mode 100644
index 000000000..1ff8f543c
--- /dev/null
+++ b/lesson_16/objects/objects_app/src/main/java/com/codedifferently/lesson16/strengthmachine/MachineInUseException.java
@@ -0,0 +1,7 @@
+package com.codedifferently.lesson16.strengthmachine;
+
+public class MachineInUseException extends RuntimeException {
+  public MachineInUseException(String message) {
+    super(message);
+  }
+}
diff --git a/lesson_16/objects/objects_app/src/main/java/com/codedifferently/lesson16/strengthmachine/StrengthMachine.java b/lesson_16/objects/objects_app/src/main/java/com/codedifferently/lesson16/strengthmachine/StrengthMachine.java
new file mode 100644
index 000000000..538823880
--- /dev/null
+++ b/lesson_16/objects/objects_app/src/main/java/com/codedifferently/lesson16/strengthmachine/StrengthMachine.java
@@ -0,0 +1,102 @@
+package com.codedifferently.lesson16.strengthmachine;
+
+import java.util.ArrayList;
+
+public class StrengthMachine {
+  private String name;
+  private int currentWeight;
+  private boolean inUse;
+  private ArrayList<String> safetyTips;
+  private MuscleGroup targetMuscle;
+
+  public enum MuscleGroup {
+    SHOULDERS,
+    CHEST,
+    ARMS,
+    LEGS,
+    BACK
+  }
+
+  public StrengthMachine(
+      String name,
+      int currentWeight,
+      boolean inUse,
+      ArrayList<String> safetyTips,
+      MuscleGroup targetMuscle) {
+    this.name = name;
+    this.currentWeight = currentWeight;
+    this.inUse = inUse;
+    this.safetyTips = safetyTips;
+    this.targetMuscle = targetMuscle;
+  }
+
+  public StrengthMachine(String name, MuscleGroup targetMuscle) {
+    this.name = name;
+    this.currentWeight = 5;
+    this.inUse = false;
+    this.safetyTips = new ArrayList<>();
+    this.targetMuscle = targetMuscle;
+  }
+
+  public boolean isAvailable() {
+    return !inUse;
+  }
+
+  public void increaseWeightGradually(int targetWeight) {
+    while (currentWeight < targetWeight) {
+      currentWeight += 5;
+    }
+  }
+
+  public void addSafetyTip(String tip) {
+    safetyTips.add(tip);
+  }
+
+  public void useMachine() {
+    if (isAvailable()) {
+      inUse = true;
+    } else {
+      throw new MachineInUseException("Cannot use - Machine currently in use");
+    }
+  }
+
+  public String getName() {
+    return name;
+  }
+
+  public void setName(String name) {
+    this.name = name;
+  }
+
+  public int getCurrentWeight() {
+    return currentWeight;
+  }
+
+  public void setCurrentWeight(int currentWeight) {
+    this.currentWeight = currentWeight;
+  }
+
+  public boolean getInUse() {
+    return inUse;
+  }
+
+  public void setInUse(boolean inUse) {
+    this.inUse = inUse;
+  }
+
+  public ArrayList<String> getSafetyTips() {
+    return safetyTips;
+  }
+
+  public void setSafetyTips(ArrayList<String> safetyTips) {
+    this.safetyTips = safetyTips;
+  }
+
+  public MuscleGroup getTargetMuscle() {
+    return targetMuscle;
+  }
+
+  public void setTargetMuscle(MuscleGroup targetMuscle) {
+    this.targetMuscle = targetMuscle;
+  }
+}
diff --git a/lesson_16/objects/objects_app/src/test/java/com/codedifferently/lesson16/strengthmachine/StrengthMachineTest.java b/lesson_16/objects/objects_app/src/test/java/com/codedifferently/lesson16/strengthmachine/StrengthMachineTest.java
new file mode 100644
index 000000000..79039a9ca
--- /dev/null
+++ b/lesson_16/objects/objects_app/src/test/java/com/codedifferently/lesson16/strengthmachine/StrengthMachineTest.java
@@ -0,0 +1,169 @@
+package com.codedifferently.lesson16.strengthmachine;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import com.codedifferently.lesson16.strengthmachine.StrengthMachine.MuscleGroup;
+import java.util.ArrayList;
+import java.util.Arrays;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class StrengthMachineTest {
+
+  StrengthMachine strengthMachine;
+
+  @BeforeEach
+  void setUp() {
+    strengthMachine =
+        new StrengthMachine(
+            "Leg Press",
+            100,
+            false,
+            new ArrayList<>(Arrays.asList("Keep back straight.", "Use a spotter for heavy lifts.")),
+            StrengthMachine.MuscleGroup.LEGS);
+  }
+
+  @Test
+  public void testIsAvailableTrue() {
+    assertTrue(strengthMachine.isAvailable());
+  }
+
+  @Test
+  public void testIsAvailableFalse() {
+    strengthMachine.useMachine();
+    assertFalse(strengthMachine.isAvailable());
+  }
+
+  @Test
+  public void testIncreaseWeightGradually() {
+    strengthMachine.increaseWeightGradually(125);
+    int actual = strengthMachine.getCurrentWeight();
+    assertThat(actual).isEqualTo(125);
+  }
+
+  @Test
+  public void testAddSafetyTip() {
+    strengthMachine.addSafetyTip("Do not lock your joints.");
+    assertThat(strengthMachine.getSafetyTips().size()).isEqualTo(3);
+  }
+
+  @Test
+  public void testUseMachineAvailable() {
+    strengthMachine.useMachine();
+    assertFalse(strengthMachine.isAvailable());
+  }
+
+  @Test
+  public void testUseMachineException() {
+    strengthMachine.useMachine();
+
+    assertThatThrownBy(() -> strengthMachine.useMachine())
+        .isInstanceOf(MachineInUseException.class)
+        .hasMessage("Cannot use - Machine currently in use");
+  }
+
+  @Test
+  public void testGetName() {
+    // Act
+    String actual = strengthMachine.getName();
+
+    // Assert
+    assertThat(actual).isEqualTo("Leg Press");
+  }
+
+  @Test
+  public void testSetName() {
+    // Act
+    strengthMachine.setName("Leg Curl");
+    String actual = strengthMachine.getName();
+
+    // Assert
+    assertThat(actual).isEqualTo("Leg Curl");
+  }
+
+  @Test
+  public void testGetCurrentWeight() {
+    // Act
+    int actual = strengthMachine.getCurrentWeight();
+
+    // Assert
+    assertThat(actual).isEqualTo(100);
+  }
+
+  @Test
+  public void testSetCurrentWeight() {
+    // Act
+    strengthMachine.setCurrentWeight(150);
+    int actual = strengthMachine.getCurrentWeight();
+
+    // Assert
+    assertThat(actual).isEqualTo(150);
+  }
+
+  @Test
+  public void testGetInUse() {
+    // Act
+    boolean actual = strengthMachine.getInUse();
+
+    // Assert
+    assertThat(actual).isEqualTo(false);
+  }
+
+  @Test
+  public void testSetInUse() {
+    // Act
+    strengthMachine.setInUse(true);
+    boolean actual = strengthMachine.getInUse();
+
+    // Assert
+    assertThat(actual).isEqualTo(true);
+  }
+
+  @Test
+  public void testGetSafetyTips() {
+    // Act
+    ArrayList<String> actual = strengthMachine.getSafetyTips();
+
+    // Assert
+    assertThat(actual.size()).isEqualTo(2);
+    assertThat(actual.get(0)).isEqualTo("Keep back straight.");
+    assertThat(actual.get(1)).isEqualTo("Use a spotter for heavy lifts.");
+  }
+
+  @Test
+  public void testSetSafetyTips() {
+    // Arrange
+    ArrayList<String> newTips =
+        new ArrayList<>(Arrays.asList("Bend knees slightly.", "Do not lock your joints."));
+    // Act
+    strengthMachine.setSafetyTips(newTips);
+    ArrayList<String> actual = strengthMachine.getSafetyTips();
+
+    // Assert
+    assertThat(actual.size()).isEqualTo(2);
+    assertThat(actual.get(0)).isEqualTo("Bend knees slightly.");
+    assertThat(actual.get(1)).isEqualTo("Do not lock your joints.");
+  }
+
+  @Test
+  public void testGetTargetMuscle() {
+    // Act
+    MuscleGroup actual = strengthMachine.getTargetMuscle();
+
+    // Assert
+    assertThat(actual).isEqualTo(StrengthMachine.MuscleGroup.LEGS);
+  }
+
+  @Test
+  public void testSetTargetMuscle() {
+    // Act
+    strengthMachine.setTargetMuscle(StrengthMachine.MuscleGroup.BACK);
+    MuscleGroup actual = strengthMachine.getTargetMuscle();
+
+    // Assert
+    assertThat(actual).isEqualTo(StrengthMachine.MuscleGroup.BACK);
+  }
+}