diff --git a/tests/Feature/AdminContentTest.php b/tests/Feature/AdminContentTest.php
index 9ace8a7..49765d0 100644
--- a/tests/Feature/AdminContentTest.php
+++ b/tests/Feature/AdminContentTest.php
@@ -407,4 +407,99 @@ class AdminContentTest extends TestCase
         $this->assertEquals(45, (int) Setting::get('calc_default_markup'));
         $this->assertEquals(8, (int) Setting::get('calc_failure_rate'));
     }
+
+    public function test_3d_print_price_calculator_service_calculates_correctly(): void
+    {
+        $calculator = app(\App\Services\PriceCalculatorService::class);
+
+        // 100 grams, 4 hours, 1 color, PLA, 40% margin
+        $result = $calculator->calculate(
+            weightGrams: 100,
+            printTimeHours: 4.0,
+            colorCount: 1,
+            material: 'pla',
+            customMarkupPercent: 40.0
+        );
+
+        $this->assertArrayHasKey('suggested_price', $result);
+        $this->assertArrayHasKey('suggested_price_formatted', $result);
+        $this->assertArrayHasKey('breakdown', $result);
+        $this->assertArrayHasKey('material_cost', $result['breakdown']);
+        $this->assertArrayHasKey('electricity_cost', $result['breakdown']);
+        $this->assertArrayHasKey('machine_cost', $result['breakdown']);
+        $this->assertArrayHasKey('total_cost_price', $result['breakdown']);
+
+        $this->assertGreaterThan(5.0, $result['suggested_price']);
+
+        // Multi-color test: 4 colors should cost more than 1 color due to purge waste & setup
+        $multiColorResult = $calculator->calculate(
+            weightGrams: 100,
+            printTimeHours: 4.0,
+            colorCount: 4,
+            material: 'pla',
+            customMarkupPercent: 40.0
+        );
+
+        $this->assertGreaterThan($result['suggested_price'], $multiColorResult['suggested_price']);
+        $this->assertGreaterThan($result['breakdown']['material_cost'], $multiColorResult['breakdown']['material_cost']);
+    }
+
+    public function test_admin_can_use_calculate_price_api_endpoint(): void
+    {
+        $response = $this->actingAs($this->admin)->postJson(route('admin.products.calculate-price'), [
+            'weight_grams' => 120,
+            'print_time_hours' => 5.5,
+            'color_count' => 2,
+            'material' => 'petg',
+            'markup_percent' => 50,
+        ]);
+
+        $response->assertStatus(200);
+        $response->assertJsonStructure([
+            'success',
+            'data' => [
+                'inputs',
+                'rates',
+                'breakdown' => [
+                    'effective_weight_grams',
+                    'material_cost',
+                    'electricity_cost',
+                    'machine_cost',
+                    'handling_cost',
+                    'failure_cost',
+                    'total_cost_price',
+                    'profit_amount',
+                    'price_excl_vat',
+                    'vat_amount',
+                    'price_incl_vat_exact',
+                ],
+                'suggested_price',
+                'suggested_price_formatted',
+            ],
+        ]);
+    }
+
+    public function test_admin_can_save_calculator_tariffs_in_content_settings(): void
+    {
+        $response = $this->actingAs($this->admin)->post(route('admin.content.update'), [
+            'calc_filament_price_kg' => '22.50',
+            'calc_electricity_kwh' => '0.40',
+            'calc_printer_wattage' => '180',
+            'calc_machine_hourly_rate' => '0.65',
+            'calc_handling_flat' => '2.00',
+            'calc_default_markup' => '45',
+            'calc_failure_rate' => '8',
+        ]);
+
+        $response->assertRedirect(route('admin.content.index'));
+        Setting::flushCache();
+
+        $this->assertEquals(22.50, (float) Setting::get('calc_filament_price_kg'));
+        $this->assertEquals(0.40, (float) Setting::get('calc_electricity_kwh'));
+        $this->assertEquals(180, (int) Setting::get('calc_printer_wattage'));
+        $this->assertEquals(0.65, (float) Setting::get('calc_machine_hourly_rate'));
+        $this->assertEquals(2.00, (float) Setting::get('calc_handling_flat'));
+        $this->assertEquals(45, (int) Setting::get('calc_default_markup'));
+        $this->assertEquals(8, (int) Setting::get('calc_failure_rate'));
+    }
 }