diff --git a/Sources/ThreeMF/Resources/Multiproperties.swift b/Sources/ThreeMF/Resources/Multiproperties.swift
index 805f36a..207bf88 100644
--- a/Sources/ThreeMF/Resources/Multiproperties.swift
+++ b/Sources/ThreeMF/Resources/Multiproperties.swift
@@ -61,8 +61,11 @@ public struct Multiproperties: Resource, XMLElementCodable {
 public extension Multiproperties {
     /// One layer of a combination: which property it takes, and how it blends onto what's beneath.
     struct Layer: Sendable {
-        let property: PropertyReference
-        let blendMethod: BlendMethod
+        /// Which entry of which property group this layer takes.
+        public let property: PropertyReference
+
+        /// How this layer combines with the ones below it.
+        public let blendMethod: BlendMethod
     }
 
     /// One combination, as layers from the base upward.
diff --git a/Sources/ThreeMF/Resources/Object/Alternatives.swift b/Sources/ThreeMF/Resources/Object/Alternatives.swift
index 76b30e7..859e8d1 100644
--- a/Sources/ThreeMF/Resources/Object/Alternatives.swift
+++ b/Sources/ThreeMF/Resources/Object/Alternatives.swift
@@ -19,7 +19,14 @@ public struct Alternative: XMLElementCodable, Sendable {
     /// How exact this alternative is, so a consumer can tell it apart from the others.
     public var modelResolution: ModelResolution?
 
-    init(objectID: ResourceID, uuid: UUID? = nil, path: URL? = nil, modelResolution: ModelResolution? = nil) {
+    /// Creates an alternative representation of an object.
+    /// - Parameters:
+    ///   - objectID: The id of the object holding this representation.
+    ///   - uuid: The identifier this alternative shares with the object it stands in for. A fresh
+    ///     one is generated when you don't give one.
+    ///   - path: The model part the alternative's object lives in, when it isn't this one.
+    ///   - modelResolution: How exact this alternative is.
+    public init(objectID: ResourceID, uuid: UUID? = nil, path: URL? = nil, modelResolution: ModelResolution? = nil) {
         self.objectID = objectID
         self.uuid = uuid ?? UUID()
         self.path = path
diff --git a/Sources/ThreeMF/Resources/Object/Mesh.TriangleSet.swift b/Sources/ThreeMF/Resources/Object/Mesh.TriangleSet.swift
index b4d7542..5b8d512 100644
--- a/Sources/ThreeMF/Resources/Object/Mesh.TriangleSet.swift
+++ b/Sources/ThreeMF/Resources/Object/Mesh.TriangleSet.swift
@@ -21,6 +21,17 @@ public extension Mesh {
         ///
         /// Written as ranges where the indices are contiguous, so a set covering a whole region stays compact.
         public var triangleIndices: IndexSet
+
+        /// Creates a triangle set.
+        /// - Parameters:
+        ///   - name: A human-readable name for the set.
+        ///   - identifier: An identifier for the set, unique within its mesh.
+        ///   - triangleIndices: The indices into ``Mesh/triangles`` that belong to this set.
+        public init(name: String, identifier: String, triangleIndices: IndexSet) {
+            self.name = name
+            self.identifier = identifier
+            self.triangleIndices = triangleIndices
+        }
     }
 }
 
diff --git a/Sources/ThreeMF/Resources/Object/Object.swift b/Sources/ThreeMF/Resources/Object/Object.swift
index 53d4794..f7aab03 100644
--- a/Sources/ThreeMF/Resources/Object/Object.swift
+++ b/Sources/ThreeMF/Resources/Object/Object.swift
@@ -171,7 +171,7 @@ public extension Object {
         case other
 
         /// The type an object has when the file doesn't say: ``ObjectType/model``.
-        static let `default` = Self.model
+        public static let `default` = Self.model
     }
 }
 
diff --git a/Sources/ThreeMF/Resources/Texture2DGroup.swift b/Sources/ThreeMF/Resources/Texture2DGroup.swift
index a2aa11a..6e58060 100644
--- a/Sources/ThreeMF/Resources/Texture2DGroup.swift
+++ b/Sources/ThreeMF/Resources/Texture2DGroup.swift
@@ -62,7 +62,11 @@ public extension Texture2DGroup {
         /// The vertical position across the image, from 0 to 1.
         public let v: Double
 
-        init(u: Double, v: Double) {
+        /// Creates a texture coordinate.
+        /// - Parameters:
+        ///   - u: The horizontal position across the image, from 0 to 1.
+        ///   - v: The vertical position across the image, from 0 to 1.
+        public init(u: Double, v: Double) {
             self.u = u
             self.v = v
         }
diff --git a/Tests/Tests/PublicAPIAccessTests.swift b/Tests/Tests/PublicAPIAccessTests.swift
new file mode 100644
index 0000000..f9209b5
--- /dev/null
+++ b/Tests/Tests/PublicAPIAccessTests.swift
@@ -0,0 +1,70 @@
+import Testing
+import Foundation
+import Nodal
+
+// Deliberately a plain import rather than `@testable`, so this file sees the package exactly as a
+// client does. Every symbol below is reachable from the public API; if one of them loses its
+// `public` again, this file stops compiling.
+import ThreeMF
+
+struct PublicAPIAccessTests {
+    @Test func `a multiproperties layer reports the property it takes and how it blends`() throws {
+        let multiproperties = Multiproperties(
+            id: 3,
+            propertyGroupIDs: [1, 2],
+            blendMethods: [.multiply],
+            multis: [[0, 1]]
+        )
+
+        let layers = try #require(multiproperties.layerSequences.first)
+        #expect(layers.count == 2)
+
+        #expect(layers[0].property == PropertyReference(groupID: 1, index: 0))
+        #expect(layers[1].property == PropertyReference(groupID: 2, index: 1))
+        #expect(layers[1].blendMethod == .multiply)
+    }
+
+    @Test func `an object's type falls back to the documented default`() {
+        let object = Object(id: 1, content: .mesh(Mesh(vertices: [], triangles: [])))
+
+        // The file said nothing, which per the spec means `.model`.
+        #expect(object.type == nil)
+        #expect(object.type ?? .default == .model)
+    }
+
+    @Test func `a triangle set can be built and handed to a mesh`() {
+        let set = Mesh.TriangleSet(name: "Top", identifier: "top", triangleIndices: IndexSet(0..<2))
+        let mesh = Mesh(vertices: [], triangles: [], triangleSets: [set])
+
+        #expect(mesh.triangleSets.count == 1)
+        #expect(mesh.triangleSets[0].name == "Top")
+        #expect(mesh.triangleSets[0].identifier == "top")
+        #expect(mesh.triangleSets[0].triangleIndices == IndexSet(0..<2))
+    }
+
+    @Test func `texture coordinates can be built and handed to a group`() {
+        let group = Texture2DGroup(id: 2, texture2DID: 1, coordinates: [
+            Texture2DGroup.Coordinate(u: 0, v: 0),
+            Texture2DGroup.Coordinate(u: 1, v: 0.5),
+        ])
+
+        #expect(group.coordinates.count == 2)
+        #expect(group.coordinates[1].u == 1)
+        #expect(group.coordinates[1].v == 0.5)
+    }
+
+    @Test func `an alternative can be built and handed to an object`() {
+        let uuid = UUID()
+        let alternative = Alternative(objectID: 7, uuid: uuid, modelResolution: .low)
+        let object = Object(
+            id: 1,
+            alternatives: [alternative],
+            content: .mesh(Mesh(vertices: [], triangles: []))
+        )
+
+        #expect(object.alternatives.count == 1)
+        #expect(object.alternatives[0].objectID == 7)
+        #expect(object.alternatives[0].uuid == uuid)
+        #expect(object.alternatives[0].modelResolution == .low)
+    }
+}