diff --git a/src/libnest2d/include/libnest2d/nester.hpp b/src/libnest2d/include/libnest2d/nester.hpp
index b35e416e7..6a59d1c5b 100644
--- a/src/libnest2d/include/libnest2d/nester.hpp
+++ b/src/libnest2d/include/libnest2d/nester.hpp
@@ -10,6 +10,7 @@
 
 #include <libnest2d/geometry_traits.hpp>
 #define LARGE_COST_TO_REJECT 1e7
+#define COST_OF_NEW_PLATE 0.1
 
 namespace libnest2d {
 
diff --git a/src/libnest2d/include/libnest2d/selections/firstfit.hpp b/src/libnest2d/include/libnest2d/selections/firstfit.hpp
index 9ce68e7ee..e3d7e8f86 100644
--- a/src/libnest2d/include/libnest2d/selections/firstfit.hpp
+++ b/src/libnest2d/include/libnest2d/selections/firstfit.hpp
@@ -140,7 +140,7 @@ public:
                     }
                     result = placers[j].pack(*it, rem(it, store_));
                     score = result.score();
-                    score_all_plates = score;
+                    score_all_plates = score + COST_OF_NEW_PLATE * j; // add a larger cost to larger plate id to encourace to use less plates
                     for (int i = 0; i < placers.size(); i++) { score_all_plates += placers[i].score();}
                     if (this->unfitindicator_)
                         this->unfitindicator_((boost::format("item %1% bed_id=%2%, score=%3%, score_all_plates=%4%, pos=(%5%, %6%)") % it->get().name % j % score %
diff --git a/src/slic3r/GUI/Jobs/ArrangeJob.cpp b/src/slic3r/GUI/Jobs/ArrangeJob.cpp
index 0174f949c..eca703bd3 100644
--- a/src/slic3r/GUI/Jobs/ArrangeJob.cpp
+++ b/src/slic3r/GUI/Jobs/ArrangeJob.cpp
@@ -481,15 +481,19 @@ void ArrangeJob::prepare_outside_plate() {
             auto iter1 = all_inside_objects.find(std::pair(obj_idx, inst_idx));
             auto iter2 = all_outside_objects.find(std::pair(obj_idx, inst_idx));
             bool outside_plate = false;
+            PartPlate *plate_locked         = nullptr;
             if (iter1 == all_inside_objects.end()) {
                 continue;
+            } else {
+                int plate_idx = iter1->second;
+                if (plate_list.get_plate(plate_idx)->is_locked()) { plate_locked = plate_list.get_plate(plate_idx); }
             }
             if (iter2 != all_outside_objects.end()) {
                 outside_plate = true;
                 ARRANGE_LOG(debug) << object->name << " is outside!";
             }
             ArrangePolygon&& ap = prepare_arrange_polygon(instance);
-            ArrangePolygons &cont = instance->printable ? (outside_plate ? m_selected : m_unselected) : m_unprintable;
+            ArrangePolygons &cont = !instance->printable ? m_unprintable : plate_locked ? m_locked : outside_plate ? m_selected : m_unselected;
             ap.itemid                      = cont.size();
             if (!outside_plate) {
                 plate_list.preprocess_arrange_polygon(obj_idx, inst_idx, ap, false);