diff --git a/src/components/download.js b/src/components/download.js
new file mode 100644
index 0000000..cbfdbc0
--- /dev/null
+++ b/src/components/download.js
@@ -0,0 +1,54 @@
+const xmlns = "http://www.w3.org/2000/xmlns/";
+const xlinkns = "http://www.w3.org/1999/xlink";
+const svgns = "http://www.w3.org/2000/svg";
+
+
+export function download(value, name = "untitled", label = "Save") {
+  console.log("in download");
+  const a = document.createElement("a");
+  const b = a.appendChild(document.createElement("button"));
+  b.textContent = label;
+  a.download = name;
+
+  async function reset() {
+    await new Promise(requestAnimationFrame);
+    URL.revokeObjectURL(a.href);
+    a.removeAttribute("href");
+    b.textContent = label;
+    b.disabled = false;
+  }
+
+  a.onclick = async event => {
+    console.log("clicked");
+    b.disabled = true;
+    if (a.href) {
+      console.log(`already saved: ${a.href}`);
+      return reset(); // Already saved.
+    }
+    b.textContent = "Saving…";
+    try {
+      const object = await (typeof value === "function" ? value() : value);
+      console.log("svg object:");
+      console.log(object);
+      b.textContent = "Download";
+      a.href = URL.createObjectURL(object); // eslint-disable-line require-atomic-updates
+      console.log(`url = ${a.href}`);
+    } catch (ignore) {
+      b.textContent = label;
+    }
+    if (event.eventPhase) return reset(); // Already downloaded.
+    b.disabled = false;
+  };
+
+  return a;
+}
+
+
+export function serialize_svg(svg) {
+  svg = svg.cloneNode(true);
+  svg.setAttributeNS(xmlns, "xmlns", svgns);
+  svg.setAttributeNS(xmlns, "xmlns:xlink", xlinkns);
+  const serializer = new window.XMLSerializer;
+  const string = serializer.serializeToString(svg);
+  return new Blob([string], {type: "image/svg+xml"});
+}