diff --git a/src/hooks/use-global-obj-loader.ts b/src/hooks/use-global-obj-loader.ts
index 69422095..fe91ee21 100644
--- a/src/hooks/use-global-obj-loader.ts
+++ b/src/hooks/use-global-obj-loader.ts
@@ -1,6 +1,7 @@
 import { useState, useEffect } from "react"
 import type { Object3D } from "three"
 import { MTLLoader, OBJLoader } from "three-stdlib"
+import { get3DModelCacheKey } from "src/utils/get-3d-model-cache-key"
 import { loadVrml } from "src/utils/vrml"
 
 // Define the type for our cache
@@ -28,7 +29,7 @@ export function useGlobalObjLoader(
   useEffect(() => {
     if (!url) return
 
-    const cleanUrl = url.replace(/&cachebust_origin=$/, "")
+    const cleanUrl = get3DModelCacheKey(url)
 
     const cache = window.TSCIRCUIT_OBJ_LOADER_CACHE
     let hasUrlChanged = false
diff --git a/src/utils/get-3d-model-cache-key.ts b/src/utils/get-3d-model-cache-key.ts
new file mode 100644
index 00000000..c1a375ed
--- /dev/null
+++ b/src/utils/get-3d-model-cache-key.ts
@@ -0,0 +1,39 @@
+/**
+ * Returns a normalized cache key for a 3D model URL.
+ *
+ * Strips the `cachebust_origin` query parameter wherever it appears in the
+ * query string, regardless of whether it has a value. `cachebust_origin`
+ * records the consumer's origin and is not meaningful to the underlying
+ * model — two URLs that differ only in `cachebust_origin` must hit the
+ * same cache entry, otherwise the same model is fetched and parsed twice.
+ *
+ * Without this normalization the in-place regex previously used in
+ * `useGlobalObjLoader` only matched the trailing empty form
+ * (`&cachebust_origin=`) and missed the filled form
+ * (`&cachebust_origin=https%3A%2F%2Ftscircuit.com`), which is what real
+ * fixtures send (see `stories/assets/complex-board.json`,
+ * `nine-key-keyboard.json`, etc.).
+ */
+export function get3DModelCacheKey(url: string): string {
+  if (!url) return url
+
+  const hashIndex = url.indexOf("#")
+  const hash = hashIndex >= 0 ? url.slice(hashIndex) : ""
+  const beforeHash = hashIndex >= 0 ? url.slice(0, hashIndex) : url
+
+  const queryIndex = beforeHash.indexOf("?")
+  if (queryIndex < 0) return beforeHash + hash
+
+  const base = beforeHash.slice(0, queryIndex)
+  const query = beforeHash.slice(queryIndex + 1)
+
+  const filteredQuery = query
+    .split("&")
+    .filter(
+      (pair) =>
+        pair !== "cachebust_origin" && !pair.startsWith("cachebust_origin="),
+    )
+    .join("&")
+
+  return filteredQuery ? `${base}?${filteredQuery}${hash}` : `${base}${hash}`
+}
diff --git a/tests/get-3d-model-cache-key.test.ts b/tests/get-3d-model-cache-key.test.ts
new file mode 100644
index 00000000..439067d8
--- /dev/null
+++ b/tests/get-3d-model-cache-key.test.ts
@@ -0,0 +1,93 @@
+import { expect, test } from "bun:test"
+import { get3DModelCacheKey } from "../src/utils/get-3d-model-cache-key"
+
+test("returns the original URL when no cachebust_origin is present", () => {
+  expect(get3DModelCacheKey("https://cdn.com/model.obj")).toBe(
+    "https://cdn.com/model.obj",
+  )
+})
+
+test("strips trailing cachebust_origin with empty value", () => {
+  expect(
+    get3DModelCacheKey("https://cdn.com/model.obj?uuid=abc&cachebust_origin="),
+  ).toBe("https://cdn.com/model.obj?uuid=abc")
+})
+
+test("strips trailing cachebust_origin with a URL-encoded value", () => {
+  expect(
+    get3DModelCacheKey(
+      "https://cdn.com/model.obj?uuid=abc&cachebust_origin=https%3A%2F%2Ftscircuit.com",
+    ),
+  ).toBe("https://cdn.com/model.obj?uuid=abc")
+})
+
+test("strips cachebust_origin when it is the only query parameter", () => {
+  expect(
+    get3DModelCacheKey("https://cdn.com/model.obj?cachebust_origin=foo"),
+  ).toBe("https://cdn.com/model.obj")
+})
+
+test("strips cachebust_origin from the start of the query and preserves following params", () => {
+  expect(
+    get3DModelCacheKey(
+      "https://cdn.com/model.obj?cachebust_origin=foo&uuid=abc",
+    ),
+  ).toBe("https://cdn.com/model.obj?uuid=abc")
+})
+
+test("strips cachebust_origin from the middle of the query", () => {
+  expect(
+    get3DModelCacheKey(
+      "https://cdn.com/model.obj?uuid=abc&cachebust_origin=foo&pn=C123",
+    ),
+  ).toBe("https://cdn.com/model.obj?uuid=abc&pn=C123")
+})
+
+test("preserves URL fragment when stripping cachebust_origin", () => {
+  expect(
+    get3DModelCacheKey(
+      "https://cdn.com/model.obj?uuid=abc&cachebust_origin=foo#section1",
+    ),
+  ).toBe("https://cdn.com/model.obj?uuid=abc#section1")
+})
+
+test("does not strip parameters with similar prefixes", () => {
+  expect(
+    get3DModelCacheKey(
+      "https://cdn.com/model.obj?cachebust_origin_extra=foo&cachebust=bar",
+    ),
+  ).toBe("https://cdn.com/model.obj?cachebust_origin_extra=foo&cachebust=bar")
+})
+
+test("returns the same value for two URLs that differ only in cachebust_origin", () => {
+  const a =
+    "https://cdn.com/model.obj?uuid=abc&cachebust_origin=https%3A%2F%2Fa.com"
+  const b =
+    "https://cdn.com/model.obj?uuid=abc&cachebust_origin=https%3A%2F%2Fb.com"
+  expect(get3DModelCacheKey(a)).toBe(get3DModelCacheKey(b))
+})
+
+test("returns the same value for trailing-empty vs filled cachebust_origin", () => {
+  const a = "https://cdn.com/model.obj?uuid=abc&cachebust_origin="
+  const b =
+    "https://cdn.com/model.obj?uuid=abc&cachebust_origin=https%3A%2F%2Ftscircuit.com"
+  expect(get3DModelCacheKey(a)).toBe(get3DModelCacheKey(b))
+})
+
+test("returns empty string when input is empty", () => {
+  expect(get3DModelCacheKey("")).toBe("")
+})
+
+test("normalizes a real production URL from complex-board fixture", () => {
+  const url =
+    "https://modelcdn.tscircuit.com/easyeda_models/download?uuid=229b69761e2c45dba6a83d8866dec72d&pn=C61423&cachebust_origin=https%3A%2F%2Ftscircuit.com"
+  const expected =
+    "https://modelcdn.tscircuit.com/easyeda_models/download?uuid=229b69761e2c45dba6a83d8866dec72d&pn=C61423"
+  expect(get3DModelCacheKey(url)).toBe(expected)
+})
+
+test("handles cachebust_origin appearing as a value-less parameter", () => {
+  expect(
+    get3DModelCacheKey("https://cdn.com/model.obj?uuid=abc&cachebust_origin"),
+  ).toBe("https://cdn.com/model.obj?uuid=abc")
+})