diff --git a/Detectors/Upgrades/ALICE3/MID/base/include/MI3Base/MI3BaseParam.h b/Detectors/Upgrades/ALICE3/MID/base/include/MI3Base/MI3BaseParam.h
index 7061a05bfeb37..913e27e85c207 100644
--- a/Detectors/Upgrades/ALICE3/MID/base/include/MI3Base/MI3BaseParam.h
+++ b/Detectors/Upgrades/ALICE3/MID/base/include/MI3Base/MI3BaseParam.h
@@ -19,7 +19,19 @@ namespace o2
 {
 namespace mi3
 {
+
+// **
+// ** Parameters for MID base configuration
+// **
+
+enum MIDLayout : int {
+  StandardRadius = 0,
+  ReducedRadius = 1
+};
+
 struct MIDBaseParam : public o2::conf::ConfigurableParamHelper<MIDBaseParam> {
+  int mLayout = MIDLayout::StandardRadius;
+
   O2ParamDef(MIDBaseParam, "MIDBase");
 };
 
diff --git a/Detectors/Upgrades/ALICE3/MID/simulation/src/Detector.cxx b/Detectors/Upgrades/ALICE3/MID/simulation/src/Detector.cxx
index 36f5b376563c0..0eaf401e40596 100644
--- a/Detectors/Upgrades/ALICE3/MID/simulation/src/Detector.cxx
+++ b/Detectors/Upgrades/ALICE3/MID/simulation/src/Detector.cxx
@@ -126,8 +126,16 @@ void Detector::createGeometry()
 
   // Build the MID
   mLayers.resize(2);
-  mLayers[0] = MIDLayer(0, GeometryTGeo::composeSymNameLayer(0), 301.f, 500.f);
-  mLayers[1] = MIDLayer(1, GeometryTGeo::composeSymNameLayer(1), 311.f, 520.f); // arbitrarily reduced to get multiple of 5.2f
+  auto& midParam = MIDBaseParam::Instance();
+  const bool standardRadius = (midParam.mLayout == o2::mi3::MIDLayout::StandardRadius);
+
+  if (standardRadius) {
+    mLayers[0] = MIDLayer(0, GeometryTGeo::composeSymNameLayer(0), 301.f, 500.f);
+    mLayers[1] = MIDLayer(1, GeometryTGeo::composeSymNameLayer(1), 311.f, 520.f); // arbitrarily reduced to get multiple of 5.2f
+  } else {
+    mLayers[0] = MIDLayer(0, GeometryTGeo::composeSymNameLayer(0), 266.f, 500.f);
+    mLayers[1] = MIDLayer(1, GeometryTGeo::composeSymNameLayer(1), 276.f, 520.f);
+  }
 
   for (auto& layer : mLayers) {
     layer.createLayer(vMID);
diff --git a/Detectors/Upgrades/ALICE3/Passive/include/Alice3DetectorsPassive/PassiveBaseParam.h b/Detectors/Upgrades/ALICE3/Passive/include/Alice3DetectorsPassive/PassiveBaseParam.h
index 3ac53c1bfb92b..671f436aabe7b 100644
--- a/Detectors/Upgrades/ALICE3/Passive/include/Alice3DetectorsPassive/PassiveBaseParam.h
+++ b/Detectors/Upgrades/ALICE3/Passive/include/Alice3DetectorsPassive/PassiveBaseParam.h
@@ -29,10 +29,16 @@ enum MagnetLayout : int {
   CopperStabilizer = 1
 };
 
+enum DetLayout : int {
+  StandardRadius = 0,
+  ReducedRadius = 1
+};
+
 struct Alice3PassiveBaseParam : public o2::conf::ConfigurableParamHelper<Alice3PassiveBaseParam> {
   // Geometry Builder parameters
 
   int mLayout = MagnetLayout::AluminiumStabilizer;
+  int mDetLayout = DetLayout::StandardRadius;
 
   O2ParamDef(Alice3PassiveBaseParam, "Alice3PassiveBase");
 };
diff --git a/Detectors/Upgrades/ALICE3/Passive/src/Absorber.cxx b/Detectors/Upgrades/ALICE3/Passive/src/Absorber.cxx
index 7ce753db89536..924d977247c89 100644
--- a/Detectors/Upgrades/ALICE3/Passive/src/Absorber.cxx
+++ b/Detectors/Upgrades/ALICE3/Passive/src/Absorber.cxx
@@ -12,6 +12,7 @@
 #include <DetectorsBase/Detector.h>
 #include <DetectorsBase/MaterialManager.h>
 #include <Alice3DetectorsPassive/Absorber.h>
+#include <Alice3DetectorsPassive/PassiveBaseParam.h>
 #include <TGeoArb8.h> // for TGeoTrap
 #include <TGeoCompositeShape.h>
 #include <TGeoCone.h>
@@ -130,25 +131,52 @@ void Alice3Absorber::ConstructGeometry()
   }
 
   TGeoPcon* absorings = new TGeoPcon(0., 360., 18);
-
-  absorings->DefineSection(0, 500, 236, 274);
-  absorings->DefineSection(1, 400, 236, 274);
-  absorings->DefineSection(2, 400, 232.5, 277.5);
-  absorings->DefineSection(3, 300, 232.5, 277.5);
-  absorings->DefineSection(4, 300, 227.5, 282.5);
-  absorings->DefineSection(5, 200, 227.5, 282.5);
-  absorings->DefineSection(6, 200, 222.5, 287.5);
-  absorings->DefineSection(7, 100, 222.5, 287.5);
-  absorings->DefineSection(8, 100, 220, 290);
-  absorings->DefineSection(9, -100, 220, 290);
-  absorings->DefineSection(10, -100, 222.5, 287.5);
-  absorings->DefineSection(11, -200, 222.5, 287.5);
-  absorings->DefineSection(12, -200, 227.5, 282.5);
-  absorings->DefineSection(13, -300, 227.5, 282.5);
-  absorings->DefineSection(14, -300, 232.5, 277.5);
-  absorings->DefineSection(15, -400, 232.5, 277.5);
-  absorings->DefineSection(16, -400, 236, 274);
-  absorings->DefineSection(17, -500, 236, 274);
+  auto& passiveBaseParam = Alice3PassiveBaseParam::Instance();
+  switch (passiveBaseParam.mDetLayout) {
+    case o2::passive::DetLayout::StandardRadius:
+      absorings->DefineSection(0, 500, 236, 274);
+      absorings->DefineSection(1, 400, 236, 274);
+      absorings->DefineSection(2, 400, 232.5, 277.5);
+      absorings->DefineSection(3, 300, 232.5, 277.5);
+      absorings->DefineSection(4, 300, 227.5, 282.5);
+      absorings->DefineSection(5, 200, 227.5, 282.5);
+      absorings->DefineSection(6, 200, 222.5, 287.5);
+      absorings->DefineSection(7, 100, 222.5, 287.5);
+      absorings->DefineSection(8, 100, 220, 290);
+      absorings->DefineSection(9, -100, 220, 290);
+      absorings->DefineSection(10, -100, 222.5, 287.5);
+      absorings->DefineSection(11, -200, 222.5, 287.5);
+      absorings->DefineSection(12, -200, 227.5, 282.5);
+      absorings->DefineSection(13, -300, 227.5, 282.5);
+      absorings->DefineSection(14, -300, 232.5, 277.5);
+      absorings->DefineSection(15, -400, 232.5, 277.5);
+      absorings->DefineSection(16, -400, 236, 274);
+      absorings->DefineSection(17, -500, 236, 274);
+      break;
+    case o2::passive::DetLayout::ReducedRadius:
+      absorings->DefineSection(0, 500, 201, 239);
+      absorings->DefineSection(1, 400, 201, 239);
+      absorings->DefineSection(2, 400, 197.5, 242.5);
+      absorings->DefineSection(3, 300, 197.5, 242.5);
+      absorings->DefineSection(4, 300, 192.5, 247.5);
+      absorings->DefineSection(5, 200, 192.5, 247.5);
+      absorings->DefineSection(6, 200, 187.5, 252.5);
+      absorings->DefineSection(7, 100, 187.5, 252.5);
+      absorings->DefineSection(8, 100, 185, 255);
+      absorings->DefineSection(9, -100, 185, 255);
+      absorings->DefineSection(10, -100, 187.5, 252.5);
+      absorings->DefineSection(11, -200, 187.5, 252.5);
+      absorings->DefineSection(12, -200, 192.5, 247.5);
+      absorings->DefineSection(13, -300, 192.5, 247.5);
+      absorings->DefineSection(14, -300, 197.5, 242.5);
+      absorings->DefineSection(15, -400, 197.5, 242.5);
+      absorings->DefineSection(16, -400, 201, 239);
+      absorings->DefineSection(17, -500, 201, 239);
+      break;
+    default:
+      LOG(fatal) << "Unknown detector layout " << passiveBaseParam.mDetLayout;
+      break;
+  }
 
   // Insert
   absorings->SetName("absorings");
diff --git a/Detectors/Upgrades/ALICE3/Passive/src/Magnet.cxx b/Detectors/Upgrades/ALICE3/Passive/src/Magnet.cxx
index 5c94c3e31a244..e6c1171829bfc 100644
--- a/Detectors/Upgrades/ALICE3/Passive/src/Magnet.cxx
+++ b/Detectors/Upgrades/ALICE3/Passive/src/Magnet.cxx
@@ -106,11 +106,41 @@ void Alice3Magnet::ConstructGeometry()
 
   // Passive Base configuration parameters
   auto& passiveBaseParam = Alice3PassiveBaseParam::Instance();
-  const bool doCopperStabilizer = (passiveBaseParam.mLayout == o2::passive::MagnetLayout::CopperStabilizer);
-  if (doCopperStabilizer) {
-    mRestMaterialThickness -= 3.3; // cm Remove the Aluminium stabiliser
-    mRestMaterialThickness += 2.2; // cm Add the Copper stabiliser
-    LOG(debug) << "Alice 3 magnet: using Copper Stabilizer with thickness " << mRestMaterialThickness << " cm";
+
+  switch (passiveBaseParam.mDetLayout) {
+    case o2::passive::DetLayout::StandardRadius:
+      // Defined in the header file
+      break;
+    case o2::passive::DetLayout::ReducedRadius:
+      mInnerWrapInnerRadius = 125.f; // cm
+      mInnerWrapThickness = 1.f;     // cm
+      mCoilInnerRadius = 145.f;      // cm
+      mCoilThickness = 0.3f;         // cm
+      mRestMaterialRadius = 145.3f;  // cm
+      mRestMaterialThickness = 6.8f; // cm
+      mOuterWrapInnerRadius = 165.f; // cm
+      mOuterWrapThickness = 3.f;     // cm
+      mZLength = 800.f;              // cm
+      break;
+    default:
+      LOG(fatal) << "Unknown detector layout " << passiveBaseParam.mDetLayout;
+      break;
+  }
+
+  bool doCopperStabilizer = false;
+  switch (passiveBaseParam.mLayout) {
+    case o2::passive::MagnetLayout::AluminiumStabilizer:
+      // Handled in the header file
+      break;
+    case o2::passive::MagnetLayout::CopperStabilizer:
+      doCopperStabilizer = true;
+      mRestMaterialThickness -= 3.3; // cm Remove the Aluminium stabiliser
+      mRestMaterialThickness += 2.2; // cm Add the Copper stabiliser
+      LOG(debug) << "Alice 3 magnet: using Copper Stabilizer with thickness " << mRestMaterialThickness << " cm";
+      break;
+    default:
+      LOG(fatal) << "Unknown magnet layout " << passiveBaseParam.mLayout;
+      break;
   }
 
   TGeoManager* geoManager = gGeoManager;