diff --git a/packages/engine/Specs/Scene/GltfBuilder.js b/packages/engine/Specs/Scene/GltfBuilder.js
deleted file mode 100644
index adb10f2f1d8..00000000000
--- a/packages/engine/Specs/Scene/GltfBuilder.js
+++ /dev/null
@@ -1,463 +0,0 @@
-import { defined, RuntimeError } from "../../index.js";
-import findAccessorMinMax from "../../Source/Scene/GltfPipeline/findAccessorMinMax.js";
-
-/**
- * A fluent interface for programmatically building a glTF.
- * @alias GltfBuilder
- * @constructor
- * @private
- */
-function GltfBuilder() {
-  this.gltf = {
-    asset: {
-      generator: "cesium-tests",
-      version: "2.0",
-    },
-    extensionsUsed: [],
-    accessors: [],
-    buffers: [],
-    bufferViews: [],
-    materials: [],
-    meshes: [],
-    nodes: [
-      {
-        mesh: 0,
-      },
-    ],
-    scenes: [
-      {
-        nodes: [0],
-      },
-    ],
-    scene: 0,
-  };
-
-  this.bufferBuilders = [];
-}
-
-/**
- * Creates a new buffer.
- * @param {string} [name] The name of the buffer.
- * @returns {GltfBufferBuilder}
- */
-GltfBuilder.prototype.buffer = function (name) {
-  const index =
-    this.gltf.buffers.push({
-      name: name,
-      byteLength: 0,
-    }) - 1;
-  const bufferBuilder = new GltfBufferBuilder(this, index);
-  this.bufferBuilders.push(bufferBuilder);
-  return bufferBuilder;
-};
-
-/**
- * Creates a new mesh.
- * @param {string} [name] The name of the mesh.
- * @returns {GltfMeshBuilder}
- */
-GltfBuilder.prototype.mesh = function (name) {
-  const index =
-    this.gltf.meshes.push({
-      name: name,
-      primitives: [],
-    }) - 1;
-
-  const meshBuilder = new GltfMeshBuilder(this, index);
-  return meshBuilder;
-};
-
-/**
- * Creates a new material.
- * @param {string} [name] The name of the material.
- * @returns {GltfMaterialBuilder}
- */
-GltfBuilder.prototype.material = function (name) {
-  const index =
-    this.gltf.materials.push({
-      name: name,
-    }) - 1;
-  const materialBuilder = new GltfMaterialBuilder(this, index);
-  return materialBuilder;
-};
-
-/**
- * Gets the built glTF JSON from this builder. Calling this a second
- * time will cause the glTF returned in the first call to be invalidated.
- * Specifically, the `uri` properties of its buffers will no longer be
- * resolvable.
- *
- * After calling this method, be sure to call {@link GltfBuilder#destroy}
- * when done with the glTF, to a void leaking buffer memory.
- */
-GltfBuilder.prototype.toGltf = function () {
-  for (let i = 0; i < this.bufferBuilders.length; ++i) {
-    const bufferBuilder = this.bufferBuilders[i];
-
-    const byteLength = bufferBuilder.viewBuilders.reduce(function (
-      byteLength,
-      viewBuilder,
-    ) {
-      return byteLength + viewBuilder.bufferView.byteLength;
-    }, 0);
-
-    const buffer = new ArrayBuffer(byteLength);
-    let nextStart = 0;
-
-    for (let j = 0; j < bufferBuilder.viewBuilders.length; ++j) {
-      const viewBuilder = bufferBuilder.viewBuilders[j];
-      viewBuilder.bufferView.byteOffset = nextStart;
-      const destBuffer =
-        viewBuilder.componentType === 5126
-          ? new Float32Array(buffer, nextStart, viewBuilder._data.length)
-          : new Uint16Array(buffer, nextStart, viewBuilder._data.length);
-      destBuffer.set(viewBuilder._data);
-      nextStart += viewBuilder.bufferView.byteLength;
-    }
-
-    bufferBuilder.buffer.byteLength = byteLength;
-
-    if (bufferBuilder.buffer.uri) {
-      URL.revokeObjectURL(bufferBuilder.buffer.uri);
-    }
-
-    bufferBuilder.buffer.uri = URL.createObjectURL(new Blob([buffer]));
-
-    bufferBuilder.buffer.extras = {
-      _pipeline: {
-        source: new Uint8Array(buffer, 0, buffer.byteLength),
-      },
-    };
-  }
-
-  const gltf = this.gltf;
-  gltf.accessors.forEach(function (accessor) {
-    const minMax = findAccessorMinMax(gltf, accessor);
-    accessor.min = minMax.min;
-    accessor.max = minMax.max;
-  });
-
-  this.bufferBuilders.forEach(function (builder) {
-    delete builder.buffer.extras;
-  });
-
-  return this.gltf;
-};
-
-/**
- * Frees memory allocated for buffers in {@link GltfBuilder@toGltf}.
- */
-GltfBuilder.prototype.destroy = function () {
-  this.bufferBuilders.forEach(function (bufferBuilder) {
-    URL.revokeObjectURL(bufferBuilder.buffer.uri);
-    bufferBuilder.buffer.uri = undefined;
-  });
-};
-
-/**
- * A fluent interface for programmatically building a glTF material.
- * @param {GltfBuilder} gltfBuilder The glTF builder.
- * @param {number} materialIndex The index of this material within the glTF.
- * @private
- */
-function GltfMaterialBuilder(gltfBuilder, materialIndex) {
-  this.gltfBuilder = gltfBuilder;
-  this.materialIndex = materialIndex;
-  this.material = this.gltfBuilder.gltf.materials[materialIndex];
-}
-
-/**
- * Defines the material using JSON.
- * @param {*} json The JSON definition of the material.
- * @returns {GltfMaterialBuilder}
- */
-GltfMaterialBuilder.prototype.json = function (json) {
-  for (const property in json) {
-    if (!json.hasOwnProperty(property)) {
-      continue;
-    }
-
-    this.material[property] = json[property];
-  }
-
-  return this;
-};
-
-/**
- * A fluent interface for building a glTF mesh.
- * @param {GltfBuilder} gltfBuilder The glTF builder.
- * @param {number} meshIndex The index of this mesh within the glTF.
- * @private
- */
-function GltfMeshBuilder(gltfBuilder, meshIndex) {
-  this.gltfBuilder = gltfBuilder;
-  this.meshIndex = meshIndex;
-  this.mesh = gltfBuilder.gltf.meshes[this.meshIndex];
-}
-
-/**
- * Creates a new primitive within this mesh.
- * @param {string} [name] The name of the primitive.
- * @returns {GltfPrimitiveBuilder}
- */
-GltfMeshBuilder.prototype.primitive = function (name) {
-  const index =
-    this.mesh.primitives.push({
-      name: name,
-      attributes: {},
-    }) - 1;
-
-  const meshBuilder = new GltfPrimitiveBuilder(this, index);
-  return meshBuilder;
-};
-
-/**
- * A fluent interface for building a glTF primitive.
- * @param {GltfMeshBuilder} gltfMeshBuilder The mesh builder.
- * @param {number} primitiveIndex The index of this primitive within the mesh.
- * @private
- */
-function GltfPrimitiveBuilder(gltfMeshBuilder, primitiveIndex) {
-  this.gltfMeshBuilder = gltfMeshBuilder;
-  this.primitiveIndex = primitiveIndex;
-  this.primitive = this.gltfMeshBuilder.mesh.primitives[this.primitiveIndex];
-}
-
-/**
- * Adds a new attribute to the primitive.
- * @param {string} semantic The semantic of the attribute.
- * @param {string} accessorName The name of the accessor referenced by this attribute.
- * @returns {GltfPrimitiveBuilder}
- */
-GltfPrimitiveBuilder.prototype.attribute = function (semantic, accessorName) {
-  const gltf = this.gltfMeshBuilder.gltfBuilder.gltf;
-  const accessorId = findAccessorByName(gltf, accessorName);
-  if (accessorId < 0) {
-    throw new RuntimeError(`Accessor named ${accessorName} not found.`);
-  }
-
-  this.primitive.attributes[semantic] = accessorId;
-  return this;
-};
-
-/**
- * Sets the name of the accessor providing this primitive's indices.
- * @param {string} accessorName The name of the accessor providing the indices.
- * @returns {GltfPrimitiveBuilder}
- */
-GltfPrimitiveBuilder.prototype.indices = function (accessorName) {
-  const gltf = this.gltfMeshBuilder.gltfBuilder.gltf;
-  const accessorId = findAccessorByName(gltf, accessorName);
-  if (accessorId < 0) {
-    throw new RuntimeError(`Accessor named ${accessorName} not found.`);
-  }
-
-  this.primitive.indices = accessorId;
-  return this;
-};
-
-/**
- * Indicates that this primitive is TRIANGLES.
- * @returns {GltfPrimitiveBuilder}
- */
-GltfPrimitiveBuilder.prototype.triangles = function () {
-  this.primitive.mode = 4;
-  return this;
-};
-
-/**
- * Sets the material applied to this primitive.
- * @param {string} materialName The name of the material.
- * @returns {GltfPrimitiveBuilder}
- */
-GltfPrimitiveBuilder.prototype.material = function (materialName) {
-  const gltf = this.gltfMeshBuilder.gltfBuilder.gltf;
-
-  for (let i = 0; i < gltf.materials.length; ++i) {
-    if (gltf.materials[i].name === materialName) {
-      this.primitive.material = i;
-      return this;
-    }
-  }
-
-  throw new RuntimeError(`Material named ${materialName} not found.`);
-};
-
-/**
- * A fluent interface for building a glTF buffer.
- * @param {GltfBuilder} gltfBuilder The glTF builder.
- * @param {number} bufferIndex The index of this buffer in the glTF.
- * @private
- */
-function GltfBufferBuilder(gltfBuilder, bufferIndex) {
-  this.gltfBuilder = gltfBuilder;
-  this.bufferIndex = bufferIndex;
-  this.buffer = this.gltfBuilder.gltf.buffers[bufferIndex];
-  this.viewBuilders = [];
-}
-
-/**
- * Creates a new vertex bufferView in this buffer.
- * @param {string} name The name of the bufferView.
- * @returns {GltfBufferViewBuilder}
- */
-GltfBufferBuilder.prototype.vertexBuffer = function (name) {
-  const index =
-    this.gltfBuilder.gltf.bufferViews.push({
-      name: name,
-      buffer: this.bufferIndex,
-      byteLength: 0,
-      target: 34962,
-    }) - 1;
-  const viewBuilder = new GltfBufferViewBuilder(this, index, 5126);
-  this.viewBuilders.push(viewBuilder);
-  return viewBuilder;
-};
-
-/**
- * Creates a new index bufferView in this buffer.
- * @param {string} name The name of the bufferView.
- * @returns {GltfBufferViewBuilder}
- */
-GltfBufferBuilder.prototype.indexBuffer = function (name) {
-  const index =
-    this.gltfBuilder.gltf.bufferViews.push({
-      name: name,
-      buffer: this.bufferIndex,
-      byteLength: 0,
-      target: 34963,
-    }) - 1;
-  const viewBuilder = new GltfBufferViewBuilder(this, index, 5123);
-  this.viewBuilders.push(viewBuilder);
-  return viewBuilder;
-};
-
-/**
- * A fluent interface for building a glTF bufferView.
- * @param {GltfBufferBuilder} bufferBuilder The buffer builder.
- * @param {GltfBufferViewBuilder} bufferViewIndex The bufferView builder.
- * @param {number} componentType The glTF `componentType` of this bufferView.
- * @private
- */
-function GltfBufferViewBuilder(bufferBuilder, bufferViewIndex, componentType) {
-  this.bufferBuilder = bufferBuilder;
-  this.bufferViewIndex = bufferViewIndex;
-  this.bufferView =
-    this.bufferBuilder.gltfBuilder.gltf.bufferViews[this.bufferViewIndex];
-  this.componentType = componentType;
-  this.elementStride = 0;
-  this.nextOffset = 0;
-  this._data = undefined;
-}
-
-Object.defineProperties(GltfBufferViewBuilder.prototype, {
-  /**
-   * Gets the number of bytes in each numeric element of this bufferView.
-   */
-  elementByteLength: {
-    get: function () {
-      return this.componentType === 5126 ? 4 : 2;
-    },
-  },
-});
-
-/**
- * Defines a `VEC3` element in this bufferView.
- * @param {string} name The name of the accessor for this element.
- * @returns {GltfBufferViewBuilder}
- */
-GltfBufferViewBuilder.prototype.vec3 = function (name) {
-  const gltf = this.bufferBuilder.gltfBuilder.gltf;
-  gltf.accessors.push({
-    name: name,
-    bufferView: this.bufferViewIndex,
-    byteOffset: this.nextOffset,
-    componentType: this.componentType,
-    count: 0,
-    type: "VEC3",
-  });
-
-  this.elementStride += 3;
-
-  const newStride = 3 * this.elementByteLength;
-  if (!defined(this.bufferView.byteStride)) {
-    this.bufferView.byteStride = newStride;
-  } else {
-    this.bufferView.byteStride += newStride;
-  }
-
-  this.nextOffset += newStride;
-
-  return this;
-};
-
-/**
- * Defines a `SCALAR` element in this bufferView.
- * @param {string} name The name of the accessor for this element.
- * @returns {GltfBufferViewBuilder}
- */
-GltfBufferViewBuilder.prototype.scalar = function (name) {
-  const gltf = this.bufferBuilder.gltfBuilder.gltf;
-  gltf.accessors.push({
-    name: name,
-    bufferView: this.bufferViewIndex,
-    byteOffset: this.nextOffset,
-    componentType: this.componentType,
-    count: 0,
-    type: "SCALAR",
-  });
-
-  this.elementStride += 1;
-
-  const newStride = this.elementByteLength;
-  if (!defined(this.bufferView.byteStride)) {
-    this.bufferView.byteStride = newStride;
-  } else {
-    this.bufferView.byteStride += newStride;
-  }
-
-  this.nextOffset += newStride;
-
-  return this;
-};
-
-/**
- * Provides this bufferView's data. All elements should be defined with
- * {@link GltfBufferViewBuilder#vec3} and {@link GltfBufferViewBuilder#scalar}
- * before calling this method.
- * @param {Array|Float32Array|Uint16Array|Uint32Array} data The data.
- * @returns {GltfBufferViewBuilder}
- */
-GltfBufferViewBuilder.prototype.data = function (data) {
-  this.bufferView.byteLength = data.length * this.elementByteLength;
-  this._data = data;
-
-  const count = data.length / this.elementStride;
-
-  const gltf = this.bufferBuilder.gltfBuilder.gltf;
-  const bufferViewIndex = this.bufferViewIndex;
-
-  gltf.accessors
-    .filter(function (accessor) {
-      return accessor.bufferView === bufferViewIndex;
-    })
-    .forEach(function (accessor) {
-      accessor.count = count;
-    });
-
-  return this;
-};
-
-function findAccessorByName(gltf, accessorName) {
-  const accessors = gltf.accessors;
-
-  for (let i = 0; i < accessors.length; ++i) {
-    if (accessors[i].name === accessorName) {
-      return i;
-    }
-  }
-
-  return -1;
-}
-
-export default GltfBuilder;