diff --git a/src/csg/levelset_3d.cpp b/src/csg/levelset_3d.cpp
index 3e7ce17be26ca97f27fc760b1a99626cf8f8ab17..50bad9003eb9d52afbd3ca8bdce3d29ff35f203f 100644
--- a/src/csg/levelset_3d.cpp
+++ b/src/csg/levelset_3d.cpp
@@ -145,10 +145,22 @@ double signed_distance_3d(const LinearExtrude &lin_ext, double xx, double yy,
 
 double signed_distance_3d(const RotateExtrude &rot_ext, double xx, double yy,
                           double zz) {
-  // TODO: support angle
+  double tt = atan(yy / xx) * 180 / M_PI;
+  if ((xx < 0 && yy >= 0) || (xx < 0 && yy < 0))
+    tt += 180; // Quadrants II & III
+  else if (xx >= 0 && yy < 0)
+    tt += 360; // Quadrant IV
+
+  double sign_t = (tt >= 0 && tt <= rot_ext.angle) ? -1.0 : 1.0;
+  double dist_t = std::min(std::fabs(rot_ext.angle - tt), std::fabs(360 - tt));
+
   auto XX = std::hypot(xx, yy);
   auto YY = zz;
-  return signed_distance_2d(rot_ext.group, XX, YY);
+  auto sd_2d = signed_distance_2d(rot_ext.group, XX, YY);
+  double sign_2d = sd_2d >= 0 ? -1.0 : 1.0;
+  auto dist_2d = std::fabs(sd_2d);
+
+  return EXTERNAL_FLOW * std::max(sign_t * dist_t, sign_2d * dist_2d);
 }
 
 double signed_distance_3d(const Polyhedron &polyhedron, double xx, double yy,
diff --git a/src/csg/parser.cpp b/src/csg/parser.cpp
index fc57aaba18ac780bb086adbb203da5a532ae5342..53352b41e38f1e215253f1a9ea96df176d7c728b 100644
--- a/src/csg/parser.cpp
+++ b/src/csg/parser.cpp
@@ -468,6 +468,12 @@ template <> struct action<extrude_rot> {
     auto &curr_attr = st.curr_attrs.back();
     rot_ext.angle = std::get<double>(curr_attr["angle"]);
 
+    if (rot_ext.angle < 0 || rot_ext.angle > 360) {
+      throw csg::Exception("action<extrude_rot>",
+                           "angle=" + std::to_string(rot_ext.angle) +
+                               "; must be between 0 and 360!");
+    }
+
     for (const auto &curr_obj : st.current_2d_group) {
       rot_ext.group.objs.push_back(curr_obj);
     }
diff --git a/src/csg/tests/levelset/extrude.t.cpp b/src/csg/tests/levelset/extrude.t.cpp
index e8d7e1b1d05e3e414501bdd85e9d1c38aaa1fc12..a9b15b0509a7b85ba8d6f7cc8242040d989c17fe 100644
--- a/src/csg/tests/levelset/extrude.t.cpp
+++ b/src/csg/tests/levelset/extrude.t.cpp
@@ -133,7 +133,7 @@ TEST_CASE("two shape linear extrude", "[Levelset Extrude]") {
 }
 
 TEST_CASE("simple torus", "[Levelset Extrude]") {
-  auto my_rot_ext = csg::RotateExtrude();
+  auto my_rot_ext = csg::RotateExtrude{.angle = 360, .group = csg::Union2D()};
 
   csg::Circle my_cir{.name = std::nullopt, .radius = 1};
   auto my_mat = csg::Mulmatrix2D({{1, 0}}, {{0, 1}});
@@ -245,4 +245,38 @@ TEST_CASE("Linear extrude of a triangle with hole", "[Levelset Primitives]") {
   }
 }
 
+TEST_CASE("sliced torus", "[Levelset Extrude]") {
+  auto my_rot_ext = csg::RotateExtrude{.angle = 45, .group = csg::Union2D()};
+
+  csg::Circle my_cir{.name = std::nullopt, .radius = 1};
+  auto my_mat = csg::Mulmatrix2D({{1, 0}}, {{0, 1}});
+  my_mat.translation = {2, 0};
+  my_mat.group.objs.push_back(my_cir);
+  my_rot_ext.group.objs.push_back(my_mat);
+
+  auto my_tree = std::make_shared<csg::Tree>();
+  my_tree->top.objs.push_back(my_rot_ext);
+  csg::CsgIF my_levelset(my_tree);
+
+  SECTION("Outside") {
+    CHECK_FALSE(0 < my_levelset(0, 0, 0));
+    CHECK_FALSE(0 < my_levelset(0.9, 0, 0));
+    CHECK_FALSE(0 < my_levelset(-0.9, 0, 0));
+    CHECK_FALSE(0 < my_levelset(2, 0, 1.1));
+    CHECK_FALSE(0 < my_levelset(-2, 0, -1.1));
+    CHECK_FALSE(0 < my_levelset(2, -0.01, 0));
+    CHECK_FALSE(0 < my_levelset(1.5, 1.6, 0.9));
+    CHECK_FALSE(0 < my_levelset(-1.1, 0.0, 0));
+    CHECK_FALSE(0 < my_levelset(1.5, 1.6, -0.5));
+    CHECK_FALSE(0 < my_levelset(-2, 0.0, -0.9));
+  }
+  SECTION("Inside") {
+    CHECK(0 < my_levelset(2, 0.01, 0));
+    CHECK(0 < my_levelset(1.1, 0.01, 0));
+    CHECK(0 < my_levelset(2, 0.01, 0.9));
+    CHECK(0 < my_levelset(1.5, 1.4, 0.9));
+    CHECK(0 < my_levelset(1.5, 1.4, -0.5));
+  }
+}
+
 } // namespace
diff --git a/src/csg/tests/parser/extrude.t.cpp b/src/csg/tests/parser/extrude.t.cpp
index 3a2b5640bf10cd6bfeb11c0fc3f92295ff1170c2..749e3c10aa93f54281a94dd62cca4517b7ee4ee0 100644
--- a/src/csg/tests/parser/extrude.t.cpp
+++ b/src/csg/tests/parser/extrude.t.cpp
@@ -46,6 +46,17 @@ angle = 90
   CHECK(yy == 3);
 }
 
+TEST_CASE("rotate extrude with bad angle", "[csg]") {
+  CHECK_THROWS_WITH(csg::parse_csg(R"(
+rotate_extrude(
+angle = 370
+) {
+    square(size = [2, 3], center = false);
+}
+)"),
+                    Catch::Contains("action<extrude_rot>"));
+}
+
 TEST_CASE("extrude two shapes", "[csg]") {
   auto st = *csg::parse_csg(R"(
 linear_extrude(