diff --git a/crates/engine/src/cmd/draw2.rs b/crates/engine/src/cmd/draw2.rs
index 68dfd5dbc..527f66624 100644
--- a/crates/engine/src/cmd/draw2.rs
+++ b/crates/engine/src/cmd/draw2.rs
@@ -1631,10 +1631,9 @@ pub(crate) fn run_rectang2(s: &mut Session, p: &Value) -> Result<Value> {
     let first = if centered { a - Vec2::new(w / 2.0, h / 2.0).rotate(rot) } else { a };
     let k = rect_kind(first, w, h, rot, fillet, ch, width, f64_or(p, "elevation", 0.0));
     let hd = s.add_entity(k)?;
+    // A rectangle has its own thickness option and does not take THICKNESS.
     let th = f64_or(p, "thickness", 0.0);
-    if th != 0.0 {
-        s.doc_mut()?.modify_entity(hd, |e| e.common.thickness = th)?;
-    }
+    s.doc_mut()?.modify_entity(hd, |e| e.common.thickness = th)?;
     added(hd)
 }
 
@@ -1683,10 +1682,8 @@ impl RectM2 {
         }
         let first = self.origin(w, h).unwrap_or(a);
         let hd = s.add_entity(rect_kind(first, w, h, self.rotation, self.fillet, self.chamfer, self.width, self.elevation))?;
-        if self.thickness != 0.0 {
-            let t = self.thickness;
-            s.doc_mut()?.modify_entity(hd, |e| e.common.thickness = t)?;
-        }
+        let t = self.thickness;
+        s.doc_mut()?.modify_entity(hd, |e| e.common.thickness = t)?;
         Ok(Step::Done)
     }
     /// The rectangle's local origin (the corner `rect_kind` draws from) for a size: the first
diff --git a/crates/engine/src/cmd/props.rs b/crates/engine/src/cmd/props.rs
index 7ef3aa687..75dc0b046 100644
--- a/crates/engine/src/cmd/props.rs
+++ b/crates/engine/src/cmd/props.rs
@@ -32,6 +32,11 @@ pub fn specs() -> Vec<CommandSpec> {
         CommandSpec::new("lweight", "Lineweight...", run_lweight).menu(&["Format", "Lineweight..."]).alias(&["lw", "lineweight"]).params("{lineweight: mm | ByLayer}"),
         CommandSpec::new("ltscale", "Linetype Scale", run_ltscale).alias(&["lts"]).params("{scale}").interactive(|_| Ok(Box::new(LtscaleM))),
         CommandSpec::new("units", "Units...", run_units).menu(&["Format", "Units..."]).alias(&["un"]).params("{lunits?: 1..5, luprec?: 0..8, aunits?: 0..4, auprec?: 0..8, insunits?}"),
+        CommandSpec::new("thickness", "Thickness", run_thickness)
+            .menu(&["Format", "Thickness"])
+            .params("{thickness} (THICKNESS: the 3D thickness given to new lines, arcs, circles, points and polylines; may be negative) → {thickness}")
+            .transparent()
+            .interactive(|_| Ok(Box::new(ThicknessM))),
         CommandSpec::new("limits", "Drawing Limits", run_limits).menu(&["Format", "Drawing Limits"]).params("{min: [x,y], max: [x,y]}"),
         CommandSpec::new("style", "Text Style...", run_style)
             .menu(&["Format", "Text Style..."])
@@ -534,6 +539,42 @@ impl Interactive for LtscaleM {
     }
 }
 
+fn run_thickness(s: &mut Session, p: &Value) -> Result<Value> {
+    let t = f64_req("thickness", p, "thickness")?;
+    if !t.is_finite() || t.abs() > 1e12 {
+        return Err(bad("thickness", "thickness is out of range"));
+    }
+    s.doc_mut()?.header.set_f64("THICKNESS", t);
+    Ok(json!({ "thickness": t }))
+}
+
+/// Format > Thickness and typed THICKNESS: "Enter new value for THICKNESS <0.0000>:".
+struct ThicknessM;
+
+impl Interactive for ThicknessM {
+    fn name(&self) -> &'static str {
+        "THICKNESS"
+    }
+    fn prompt(&self, s: &Session) -> Prompt {
+        let cur = s.doc().map(|d| d.header.f64("THICKNESS", 0.0)).unwrap_or(0.0);
+        Prompt::new("Enter new value for THICKNESS", Accept::NUMBER).default(format!("{cur:.4}"))
+    }
+    fn input(&mut self, s: &mut Session, i: Input) -> Result<Step> {
+        let text = match i {
+            Input::Enter | Input::Cancel => return Ok(Step::Done),
+            Input::Text(t) => t,
+            _ => return Ok(Step::Continue),
+        };
+        match super::machines::number(&text).map(|t| run_thickness(s, &json!({ "thickness": t }))) {
+            Some(Ok(_)) => Ok(Step::Done),
+            _ => {
+                s.echo("Requires a number.");
+                Ok(Step::Continue)
+            }
+        }
+    }
+}
+
 fn run_units(s: &mut Session, p: &Value) -> Result<Value> {
     let d = s.doc_mut()?;
     for (k, lo, hi) in [("lunits", 1, 5), ("luprec", 0, 8), ("aunits", 0, 4), ("auprec", 0, 8), ("insunits", 0, 24)] {
diff --git a/crates/engine/src/lib.rs b/crates/engine/src/lib.rs
index 117db5813..e37aadbdd 100644
--- a/crates/engine/src/lib.rs
+++ b/crates/engine/src/lib.rs
@@ -885,6 +885,19 @@ impl Session {
         if d.annotative_by_style(&kind) {
             common.anno_scales = vec![d.current_anno_scale()];
         }
+        // Lines, arcs, circles, points, polylines and 2D solids take the current 3D thickness
+        // (THICKNESS). RECTANG sets its own, and text never takes it.
+        if matches!(
+            kind,
+            EntityKind::Line(_)
+                | EntityKind::Arc(_)
+                | EntityKind::Circle(_)
+                | EntityKind::Point(_)
+                | EntityKind::LwPolyline(_)
+                | EntityKind::Solid(_)
+        ) {
+            common.thickness = Some(d.header.f64("THICKNESS", 0.0)).filter(|t| t.is_finite()).unwrap_or(0.0);
+        }
         let h = self.doc_mut()?.add(&space, common, kind)?;
         Ok(h)
     }
diff --git a/crates/engine/src/tests.rs b/crates/engine/src/tests.rs
index a6c4c41d2..731256107 100644
--- a/crates/engine/src/tests.rs
+++ b/crates/engine/src/tests.rs
@@ -1309,6 +1309,58 @@ fn typed_ltscale_asks_for_the_scale() {
     assert_eq!(s.doc().unwrap().header.f64("LTSCALE", 0.0), 0.1);
 }
 
+#[test]
+fn format_thickness_asks_for_the_thickness() {
+    let mut s = Session::new();
+    s.start("thickness").unwrap();
+    assert!(s.prompt_text().contains("Enter new value for THICKNESS <0.0000>"), "{}", s.prompt_text());
+    // After text that is not a number, the prompt asks again.
+    s.cmdline("thick").unwrap();
+    assert!(s.current_prompt().is_some(), "asked again");
+    // A negative thickness is accepted.
+    s.cmdline("-1.5").unwrap();
+    assert!(s.current_prompt().is_none());
+    assert_eq!(s.doc().unwrap().header.f64("THICKNESS", 0.0), -1.5);
+    // Typed, Enter keeps the current thickness.
+    s.cmdline("thickness").unwrap();
+    assert!(s.prompt_text().contains("<-1.5000>"), "{}", s.prompt_text());
+    s.cmdline("").unwrap();
+    assert!(s.current_prompt().is_none());
+    assert_eq!(s.doc().unwrap().header.f64("THICKNESS", 0.0), -1.5);
+    assert!(s.execute("thickness", &json!({"thickness": "thick"})).is_err());
+    assert!(s.execute("thickness", &json!({"thickness": 1e13})).is_err());
+}
+
+#[test]
+fn new_objects_take_the_current_thickness() {
+    let mut s = Session::new();
+    s.execute("thickness", &json!({"thickness": 2.5})).unwrap();
+    s.execute("line", &json!({"points": [[0, 0], [10, 0]]})).unwrap();
+    s.execute("arc", &json!({"center": [0, 0], "radius": 3, "start": 0, "end": 90})).unwrap();
+    s.execute("circle", &json!({"center": [0, 0], "radius": 5})).unwrap();
+    s.execute("point", &json!({"at": [1, 1]})).unwrap();
+    s.execute("pline", &json!({"vertices": [[0, 0], [5, 0], [5, 5]]})).unwrap();
+    s.execute("polygon", &json!({"sides": 6, "center": [20, 20], "radius": 2})).unwrap();
+    s.execute("donut", &json!({"center": [30, 30], "inside": 1, "outside": 2})).unwrap();
+    let thick: Vec<(&str, f64)> = s.doc().unwrap().model.iter().map(|e| (e.kind.type_name(), e.common.thickness)).collect();
+    assert_eq!(thick.len(), 7, "{thick:?}");
+    assert!(thick.iter().all(|(_, t)| *t == 2.5), "{thick:?}");
+    // RECTANG keeps its own thickness option, and text does not take THICKNESS.
+    s.execute("rectang", &json!({"p1": [0, 0], "p2": [4, 4]})).unwrap();
+    assert_eq!(s.doc().unwrap().model.last().unwrap().common.thickness, 0.0);
+    s.execute("rectang", &json!({"p1": [0, 0], "p2": [4, 4], "thickness": 1})).unwrap();
+    assert_eq!(s.doc().unwrap().model.last().unwrap().common.thickness, 1.0);
+    let before = s.doc().unwrap().model.len();
+    s.cmdline("rectang 0,0 4,4").unwrap();
+    assert_eq!(s.doc().unwrap().model.len(), before + 1);
+    assert_eq!(s.doc().unwrap().model.last().unwrap().common.thickness, 0.0);
+    s.execute("text", &json!({"at": [0, 0], "text": "A"})).unwrap();
+    assert_eq!(s.doc().unwrap().model.last().unwrap().common.thickness, 0.0);
+    // An ellipse has no thickness.
+    s.execute("ellipse", &json!({"center": [0, 0], "major": [4, 0], "ratio": 0.5})).unwrap();
+    assert_eq!(s.doc().unwrap().model.last().unwrap().common.thickness, 0.0);
+}
+
 fn setvar_prompt_open(s: &Session) -> bool {
     s.running.as_ref().is_some_and(|r| r.id == "setvar")
 }
diff --git a/docs/parity-checklist.md b/docs/parity-checklist.md
index 5e1c7cf7f..a25961050 100644
--- a/docs/parity-checklist.md
+++ b/docs/parity-checklist.md
@@ -1,11 +1,10 @@
 # Parity checklist
 
-> **Generated:** 2026-10-15 by `cargo xtask parity`. Do not edit by hand.
-> **Generated:** 2026-10-16 by `cargo xtask parity`. Do not edit by hand.
+> **Generated:** 2026-10-24 by `cargo xtask parity`. Do not edit by hand.
 
 Menu-breadth parity: a reference menu item counts as covered when a CADCraft command is registered under the same menu label. It measures breadth, not depth; see [target-app-parity.md](target-app-parity.md) for the weighted assessment.
 
-**Menu breadth: 283 / 491 items (58%)** · 427 registered commands.
+**Menu breadth: 288 / 491 items (59%)** · 434 registered commands.
 
 | Menu | Items | Covered | % |
 |---|---|---|---|
@@ -13,8 +12,8 @@ Menu-breadth parity: a reference menu item counts as covered when a CADCraft com
 | Edit | 13 | 11 | 85% |
 | View | 75 | 31 | 41% |
 | Insert | 11 | 5 | 45% |
-| Format | 27 | 25 | 93% |
-| Tools | 85 | 60 | 71% |
+| Format | 27 | 26 | 96% |
+| Tools | 85 | 64 | 75% |
 | Draw | 87 | 55 | 63% |
 | Dimension | 28 | 28 | 100% |
 | Modify | 113 | 52 | 46% |
@@ -85,7 +84,6 @@ Menu-breadth parity: a reference menu item counts as covered when a CADCraft com
 - Insert > ACIS File...
 - Insert > Drawing Exchange Binary...
 - Format > Transparency
-- Format > Thickness
 - Tools > Spelling
 - Tools > Inquiry > Volume
 - Tools > Update Fields
@@ -101,13 +99,8 @@ Menu-breadth parity: a reference menu item counts as covered when a CADCraft com
 - Tools > New UCS > Z
 - Tools > Named UCS...
 - Tools > Customize > Interface (CUI)...
-- Tools > Customize > Edit Command Aliases (PGP)...
 - Tools > Import Settings
 - Tools > Export Settings
-- Tools > Express Tools > Convert Text to Mtext
-- Tools > Express Tools > Break-line Symbol
-- Tools > Express Tools > Move/Copy/Rotate
-- Tools > Express Tools > Explode Attributes to Text
 - Tools > Express Tools > Replace Block...
 - Tools > Express Tools > Super Hatch > Image...
 - Tools > Express Tools > Super Hatch > Xref...