diff --git a/src/three-components/STLModel.tsx b/src/three-components/STLModel.tsx
index e5c41e9d..98aa66b7 100644
--- a/src/three-components/STLModel.tsx
+++ b/src/three-components/STLModel.tsx
@@ -1,13 +1,13 @@
-import { useState, useEffect, useMemo } from "react"
+import { useEffect, useMemo, useState } from "react"
+import { useThree } from "src/react-three/ThreeContext"
 import * as THREE from "three"
 import { STLLoader } from "three-stdlib"
-import { useThree } from "src/react-three/ThreeContext"
 import type { LayerType } from "../hooks/use-stls-from-geom"
+import { loadCachedStlGeometry } from "../utils/load-cached-stl-geometry"
 
 export function STLModel({
   stlUrl,
   stlData,
-  mtlUrl,
   color,
   opacity = 1,
   layerType,
@@ -23,8 +23,8 @@ export function STLModel({
   const [geom, setGeom] = useState<THREE.BufferGeometry | null>(null)
 
   useEffect(() => {
-    const loader = new STLLoader()
     if (stlData) {
+      const loader = new STLLoader()
       try {
         const geometry = loader.parse(stlData)
         setGeom(geometry)
@@ -35,10 +35,27 @@ export function STLModel({
       return
     }
     if (stlUrl) {
-      loader.load(stlUrl, (geometry) => {
-        setGeom(geometry)
-      })
+      let isMounted = true
+      loadCachedStlGeometry(stlUrl)
+        .then((geometry) => {
+          if (!isMounted) {
+            geometry.dispose()
+            return
+          }
+          setGeom(geometry)
+        })
+        .catch((error) => {
+          if (!isMounted) return
+          console.error(`Failed to load STL model from ${stlUrl}`, error)
+          setGeom(null)
+        })
+
+      return () => {
+        isMounted = false
+      }
     }
+
+    setGeom(null)
   }, [stlUrl, stlData])
 
   const mesh = useMemo(() => {
@@ -66,7 +83,9 @@ export function STLModel({
       rootObject.remove(mesh)
       mesh.geometry.dispose()
       if (Array.isArray(mesh.material)) {
-        mesh.material.forEach((m) => m.dispose())
+        for (const material of mesh.material) {
+          material.dispose()
+        }
       } else {
         mesh.material.dispose()
       }
diff --git a/src/utils/load-cached-stl-geometry.ts b/src/utils/load-cached-stl-geometry.ts
new file mode 100644
index 00000000..d601c162
--- /dev/null
+++ b/src/utils/load-cached-stl-geometry.ts
@@ -0,0 +1,67 @@
+import type * as THREE from "three"
+import { STLLoader } from "three-stdlib"
+
+type StlLoaderLike = {
+  load: (
+    url: string,
+    onLoad: (geometry: THREE.BufferGeometry) => void,
+    onProgress?: (event: ProgressEvent) => void,
+    onError?: (error: unknown) => void,
+  ) => void
+}
+
+const stlGeometryCache = new Map<string, Promise<THREE.BufferGeometry>>()
+
+export function normalizeStlUrlCacheKey(stlUrl: string): string {
+  try {
+    const parsedUrl = new URL(stlUrl, "https://cache-key.invalid")
+    const isRelativeUrl = parsedUrl.origin === "https://cache-key.invalid"
+    parsedUrl.searchParams.delete("cachebust_origin")
+
+    if (isRelativeUrl) {
+      return `${parsedUrl.pathname}${parsedUrl.search}${parsedUrl.hash}`
+    }
+
+    return parsedUrl.toString()
+  } catch {
+    const hashParts = stlUrl.split("#", 2)
+    const urlWithoutHash = hashParts[0] ?? ""
+    const hash = hashParts[1] ?? ""
+    const [pathname, query = ""] = urlWithoutHash.split("?", 2)
+    const filteredQuery = query
+      .split("&")
+      .filter((part) => part.split("=", 1)[0] !== "cachebust_origin")
+      .join("&")
+
+    return `${pathname}${filteredQuery ? `?${filteredQuery}` : ""}${
+      hash ? `#${hash}` : ""
+    }`
+  }
+}
+
+export function clearStlGeometryCache() {
+  stlGeometryCache.clear()
+}
+
+export async function loadCachedStlGeometry(
+  stlUrl: string,
+  createLoader: () => StlLoaderLike = () =>
+    new STLLoader() as unknown as StlLoaderLike,
+): Promise<THREE.BufferGeometry> {
+  const cacheKey = normalizeStlUrlCacheKey(stlUrl)
+  let geometryPromise = stlGeometryCache.get(cacheKey)
+
+  if (!geometryPromise) {
+    geometryPromise = new Promise<THREE.BufferGeometry>((resolve, reject) => {
+      createLoader().load(stlUrl, resolve, undefined, reject)
+    }).catch((error) => {
+      stlGeometryCache.delete(cacheKey)
+      throw error
+    })
+
+    stlGeometryCache.set(cacheKey, geometryPromise)
+  }
+
+  const geometry = await geometryPromise
+  return geometry.clone()
+}
diff --git a/tests/load-cached-stl-geometry.test.ts b/tests/load-cached-stl-geometry.test.ts
new file mode 100644
index 00000000..a61ab5b0
--- /dev/null
+++ b/tests/load-cached-stl-geometry.test.ts
@@ -0,0 +1,80 @@
+import { beforeEach, expect, test } from "bun:test"
+import * as THREE from "three"
+import {
+  clearStlGeometryCache,
+  loadCachedStlGeometry,
+  normalizeStlUrlCacheKey,
+} from "../src/utils/load-cached-stl-geometry"
+
+beforeEach(() => {
+  clearStlGeometryCache()
+})
+
+test("normalizes cachebust_origin out of STL cache keys", () => {
+  expect(
+    normalizeStlUrlCacheKey(
+      "https://models.example.com/part.stl?uuid=abc&cachebust_origin=preview#mesh",
+    ),
+  ).toBe("https://models.example.com/part.stl?uuid=abc#mesh")
+  expect(
+    normalizeStlUrlCacheKey("/models/part.stl?cachebust_origin=one&uuid=abc"),
+  ).toBe("/models/part.stl?uuid=abc")
+})
+
+test("deduplicates concurrent STL loads for equivalent cache-busted URLs", async () => {
+  const loadedUrls: string[] = []
+  const templateGeometry = new THREE.BufferGeometry()
+  templateGeometry.setAttribute(
+    "position",
+    new THREE.BufferAttribute(new Float32Array([0, 0, 0, 1, 0, 0]), 3),
+  )
+
+  const createLoader = () => ({
+    load: (url: string, onLoad: (geometry: THREE.BufferGeometry) => void) => {
+      loadedUrls.push(url)
+      queueMicrotask(() => onLoad(templateGeometry))
+    },
+  })
+
+  const [first, second] = await Promise.all([
+    loadCachedStlGeometry(
+      "/models/part.stl?cachebust_origin=first&uuid=abc",
+      createLoader,
+    ),
+    loadCachedStlGeometry(
+      "/models/part.stl?uuid=abc&cachebust_origin=second",
+      createLoader,
+    ),
+  ])
+
+  expect(loadedUrls).toEqual([
+    "/models/part.stl?cachebust_origin=first&uuid=abc",
+  ])
+  expect(first).not.toBe(templateGeometry)
+  expect(second).not.toBe(templateGeometry)
+  expect(first).not.toBe(second)
+})
+
+test("does not cache failed STL loads", async () => {
+  let attempts = 0
+  const createLoader = () => ({
+    load: (
+      _url: string,
+      _onLoad: (geometry: THREE.BufferGeometry) => void,
+      _onProgress: unknown,
+      onError?: (error: Error) => void,
+    ) => {
+      attempts += 1
+      queueMicrotask(() => onError?.(new Error("failed")))
+    },
+  })
+
+  await expect(
+    loadCachedStlGeometry("/models/broken.stl", createLoader),
+  ).rejects.toThrow("failed")
+  await expect(
+    loadCachedStlGeometry("/models/broken.stl", createLoader),
+  ).rejects.toThrow("failed")
+
+  expect(attempts).toBe(2)
+})