diff --git a/rebuild.sh b/rebuild.sh
new file mode 100755
index 0000000..a862465
--- /dev/null
+++ b/rebuild.sh
@@ -0,0 +1,66 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+IMG="$HOME/Documents/toes-image-builder/toes-ubuntu-base.img"
+USBBOOT="$HOME/apps/forks/usbboot"
+
+list_external_disks() {
+  diskutil list external physical 2>/dev/null | awk '/^\/dev\/disk[0-9]+ / { sub("^/dev/", "", $1); print $1 }' | sort || true
+}
+
+disk_bytes() {
+  diskutil info "/dev/$1" | awk -F'[()]' '/Disk Size:/ { sub(/ Bytes.*/, "", $2); print $2; exit }'
+}
+
+if [[ "${SKIP_BUILD:-0}" != 1 ]]; then
+  ssh toes-image-builder 'cd toes-image-builder && ./build.sh && cp build/toes-ubuntu-base.img /mnt/utm/toes-image-builder/'
+fi
+
+[[ -f "$IMG" ]] || { echo "missing $IMG" >&2; exit 1; }
+
+target="${DISK:-}"
+if [[ -n "$target" ]]; then
+  target="${target#/dev/}"
+  target="${target#r}"
+else
+  before="$(mktemp)"
+  after="$(mktemp)"
+  trap 'rm -f "$before" "$after"' EXIT
+  list_external_disks >"$before"
+  sudo "$USBBOOT/rpiboot" -d "$USBBOOT/mass-storage-gadget64"
+
+  for _ in {1..30}; do
+    list_external_disks >"$after"
+    new="$(comm -13 "$before" "$after")"
+    [[ -n "$new" ]] && { sleep 2; list_external_disks >"$after"; new="$(comm -13 "$before" "$after")"; break; }
+    sleep 1
+  done
+  [[ -n "${new:-}" ]] || { echo "no new disks" >&2; exit 1; }
+
+  echo "New disks:"
+  target_size=0
+  for disk in $new; do
+    bytes="$(disk_bytes "$disk")"
+    echo "  /dev/$disk ${bytes:-?} bytes"
+    [[ "$bytes" =~ ^[0-9]+$ ]] && (( bytes > target_size )) && { target="$disk"; target_size="$bytes"; }
+  done
+fi
+
+[[ "${target:-}" =~ ^disk[0-9]+$ ]] || { echo "bad disk: ${target:-}" >&2; exit 1; }
+
+target_size="$(disk_bytes "$target")"
+image_size="$(stat -f %z "$IMG")"
+[[ "$target_size" =~ ^[0-9]+$ ]] || { echo "could not size /dev/$target" >&2; exit 1; }
+(( target_size >= image_size )) || { echo "/dev/$target is smaller than $IMG" >&2; exit 1; }
+
+echo "Selected /dev/$target"
+echo "Image: $IMG"
+diskutil info "/dev/$target"
+printf 'Type FLASH to erase /dev/%s: ' "$target"
+read -r answer
+[[ "$answer" == FLASH ]] || { echo "aborted"; exit 1; }
+
+diskutil unmountDisk "/dev/$target"
+sudo dd if="$IMG" of="/dev/r$target" bs=16m status=progress conv=fsync
+sync
+diskutil eject "/dev/$target"