diff --git a/addon_examples/local_anim.py b/addon_examples/local_anim.py
index a2b49b3..b582dec 100644
--- a/addon_examples/local_anim.py
+++ b/addon_examples/local_anim.py
@@ -5,6 +5,7 @@ Local animations
  assuming you loaded something.anim
 /524 start_local_anim something
 /524 stop_local_anim something
+/524 save_local_anim something
 
 If you want to trigger the animation from an object to simulate llStartAnimation():
 llOwnerSay("@start_local_anim:something=force");
@@ -21,6 +22,7 @@ bulk upload, like changing priority or removing a joint.
 import asyncio
 import os
 import pathlib
+from abc import abstractmethod
 from typing import *
 
 from hippolyzer.lib.base import serialization as se
@@ -47,6 +49,8 @@ def _get_mtime(path: str):
 class LocalAnimAddon(BaseAddon):
     # name -> path, only for anims actually from files
     local_anim_paths: Dict[str, str] = SessionProperty(dict)
+    # name -> anim bytes
+    local_anim_bytes: Dict[str, bytes] = SessionProperty(dict)
     # name -> mtime or None. Only for anims from files.
     local_anim_mtimes: Dict[str, Optional[float]] = SessionProperty(dict)
     # name -> current asset ID (changes each play)
@@ -83,6 +87,18 @@ class LocalAnimAddon(BaseAddon):
         """Stop a named local animation"""
         self.apply_local_anim(session, region, anim_name, new_data=None)
 
+    @handle_command(anim_name=str)
+    async def save_local_anim(self, _session: Session, _region: ProxiedRegion, anim_name: str):
+        """Save a named local anim to disk"""
+        anim_bytes = self.local_anim_bytes.get(anim_name)
+        if not anim_bytes:
+            return
+        filename = await AddonManager.UI.save_file(filter_str="SL Anim (*.anim)", default_suffix="anim")
+        if not filename:
+            return
+        with open(filename, "wb") as f:
+            f.write(anim_bytes)
+
     async def _try_reload_anims(self, session: Session):
         while True:
             region = session.main_region
@@ -144,9 +160,11 @@ class LocalAnimAddon(BaseAddon):
                 StartAnim=True,
             ))
             cls.local_anim_playing_ids[anim_name] = next_id
+            cls.local_anim_bytes[anim_name] = new_data
         else:
             # No data means just stop the anim
             cls.local_anim_playing_ids.pop(anim_name, None)
+            cls.local_anim_bytes.pop(anim_name, None)
 
         region.circuit.send_message(new_msg)
         print(f"Changing {anim_name} to {next_id}")
@@ -216,7 +234,7 @@ class LocalAnimAddon(BaseAddon):
 
 
 class BaseAnimManglerAddon(BaseAddon):
-    """Base class for addons that mangle uploaded or local animations"""
+    """Base class for addons that mangle uploaded or file-based local animations"""
     ANIM_MANGLERS: List[Callable[[Animation], Animation]]
 
     def handle_init(self, session_manager: SessionManager):
@@ -233,4 +251,34 @@ class BaseAnimManglerAddon(BaseAddon):
         LocalAnimAddon.remangle_local_anims(session_manager)
 
 
+class BaseAnimHelperAddon(BaseAddon):
+    """
+    Base class for local creation of procedural animations
+
+    Animation generated by build_anim() gets applied to all active sessions
+    """
+    ANIM_NAME: str
+
+    def handle_session_init(self, session: Session):
+        self._reapply_anim(session, session.main_region)
+
+    def handle_session_closed(self, session: Session):
+        LocalAnimAddon.apply_local_anim(session, session.main_region, self.ANIM_NAME, None)
+
+    def handle_unload(self, session_manager: SessionManager):
+        for session in session_manager.sessions:
+            # TODO: Nasty. Since we need to access session-local attrs we need to set the
+            #  context even though we also explicitly pass session and region.
+            #  Need to rethink the LocalAnimAddon API.
+            with addon_ctx.push(session, session.main_region):
+                LocalAnimAddon.apply_local_anim(session, session.main_region, self.ANIM_NAME, None)
+
+    @abstractmethod
+    def build_anim(self) -> Animation:
+        pass
+
+    def _reapply_anim(self, session: Session, region: ProxiedRegion):
+        LocalAnimAddon.apply_local_anim(session, region, self.ANIM_NAME, self.build_anim().to_bytes())
+
+
 addons = [LocalAnimAddon()]
diff --git a/addon_examples/tail_anim.py b/addon_examples/tail_anim.py
new file mode 100644
index 0000000..3cf8d93
--- /dev/null
+++ b/addon_examples/tail_anim.py
@@ -0,0 +1,55 @@
+"""
+Tail animation generator
+
+Demonstrates programmatic generation of local motions using BaseAnimHelperAddon
+
+You can use this to create an animation with a script, fiddle with it until it
+looks right, then finally save it with /524 save_local_anim <ANIM_NAME>.
+
+The built animation is automatically applied to all active sessions when loaded,
+and is re-generated whenever the script is edited. Unloading the script stops
+the animations.
+"""
+
+from hippolyzer.lib.base.anim_utils import shift_keyframes, smooth_rot
+from hippolyzer.lib.base.datatypes import Quaternion
+from hippolyzer.lib.base.llanim import Animation, Joint
+from hippolyzer.lib.proxy.addons import AddonManager
+
+import local_anim
+AddonManager.hot_reload(local_anim, require_addons_loaded=True)
+
+
+class TailAnimator(local_anim.BaseAnimHelperAddon):
+    # Should be unique
+    ANIM_NAME = "tail_anim"
+
+    def build_anim(self) -> Animation:
+        anim = Animation(
+            base_priority=5,
+            duration=5.0,
+            loop_out_point=5.0,
+            loop=True,
+        )
+        # Iterate along tail joints 1 through 6
+        for joint_num in range(1, 7):
+            # Give further along joints a wider range of motion
+            start_rot = Quaternion.from_euler(0.2, -0.3, 0.15 * joint_num)
+            end_rot = Quaternion.from_euler(-0.2, -0.3, -0.15 * joint_num)
+            rot_keyframes = [
+                # Tween between start_rot and end_rot, using smooth interpolation.
+                # SL's keyframes only allow linear interpolation which doesn't look great
+                # for natural motions. `smooth_rot()` gets around that by generating
+                # smooth inter frames for SL to linearly interpolate between.
+                *smooth_rot(start_rot, end_rot, inter_frames=10, time=0.0, duration=2.5),
+                *smooth_rot(end_rot, start_rot, inter_frames=10, time=2.5, duration=2.5),
+            ]
+            anim.joints[f"mTail{joint_num}"] = Joint(
+                priority=5,
+                # Each joint's frames should be ahead of the previous joint's by 2 frames
+                rot_keyframes=shift_keyframes(rot_keyframes, joint_num * 2),
+            )
+        return anim
+
+
+addons = [TailAnimator()]
diff --git a/hippolyzer/lib/base/anim_utils.py b/hippolyzer/lib/base/anim_utils.py
new file mode 100644
index 0000000..42855ac
--- /dev/null
+++ b/hippolyzer/lib/base/anim_utils.py
@@ -0,0 +1,91 @@
+"""
+Assorted utilities to make creating animations from scratch easier
+"""
+
+import copy
+from typing import List, Union
+
+from hippolyzer.lib.base.datatypes import Vector3, Quaternion
+from hippolyzer.lib.base.llanim import PosKeyframe, RotKeyframe
+
+
+def smooth_step(t: float):
+    t = max(0.0, min(1.0, t))
+    return t * t * (3 - 2 * t)
+
+
+def rot_interp(r0: Quaternion, r1: Quaternion, t: float):
+    """
+    Bad quaternion interpolation
+
+    TODO: This is definitely not correct yet seems to work ok? Implement slerp.
+    """
+    # Ignore W
+    r0 = r0.data(3)
+    r1 = r1.data(3)
+    return Quaternion(*map(lambda pair: ((pair[0] * (1.0 - t)) + (pair[1] * t)), zip(r0, r1)))
+
+
+def unique_frames(frames: List[Union[PosKeyframe, RotKeyframe]]):
+    """Drop frames where time and coordinate are exact duplicates of another frame"""
+    new_frames = []
+    for frame in frames:
+        # TODO: fudge factor for float comparison instead
+        if frame not in new_frames:
+            new_frames.append(frame)
+    return new_frames
+
+
+def shift_keyframes(frames: List[Union[PosKeyframe, RotKeyframe]], num: int):
+    """
+    Shift keyframes around by `num` frames
+
+    Assumes keyframes occur at a set cadence, and that first and last keyframe are at the same coord.
+    """
+
+    # Get rid of duplicate frames
+    frames = unique_frames(frames)
+    pop_idx = -1
+    insert_idx = 0
+    if num < 0:
+        insert_idx = len(frames) - 1
+        pop_idx = 0
+        num = -num
+    old_times = [f.time for f in frames]
+    new_frames = frames.copy()
+    # Drop last, duped frame. We'll copy the first frame to replace it later
+    new_frames.pop(-1)
+    for _ in range(num):
+        new_frames.insert(insert_idx, new_frames.pop(pop_idx))
+
+    # Put first frame back on the end
+    new_frames.append(copy.copy(new_frames[0]))
+
+    assert len(old_times) == len(new_frames)
+    assert new_frames[0] == new_frames[-1]
+    # Make the times of the shifted keyframes match up with the previous timeline
+    for old_time, new_frame in zip(old_times, new_frames):
+        new_frame.time = old_time
+    return new_frames
+
+
+def smooth_pos(start: Vector3, end: Vector3, inter_frames: int, time: float, duration: float) -> List[PosKeyframe]:
+    """Generate keyframes to smoothly interpolate between two positions"""
+    frames = [PosKeyframe(time=time, pos=start)]
+    for i in range(0, inter_frames):
+        t = (i + 1) / (inter_frames + 1)
+        smooth_t = smooth_step(t)
+        pos = Vector3(smooth_t, smooth_t, smooth_t).interpolate(start, end)
+        frames.append(PosKeyframe(time=time + (t * duration), pos=pos))
+    return frames + [PosKeyframe(time=time + duration, pos=end)]
+
+
+def smooth_rot(start: Quaternion, end: Quaternion, inter_frames: int, time: float, duration: float)\
+        -> List[RotKeyframe]:
+    """Generate keyframes to smoothly interpolate between two rotations"""
+    frames = [RotKeyframe(time=time, rot=start)]
+    for i in range(0, inter_frames):
+        t = (i + 1) / (inter_frames + 1)
+        smooth_t = smooth_step(t)
+        frames.append(RotKeyframe(time=time + (t * duration), rot=rot_interp(start, end, smooth_t)))
+    return frames + [RotKeyframe(time=time + duration, rot=end)]