Auto is onSwitch to MANUAL and aim it yourself, or SCAN and it sweeps the room.
CAM 1280×800 · MODE AUTO · 24 FPS
SIMThe demos on this page are simulations, not footage from a turret. In the HUD demo a hit pops the balloon for fun. On the real turret, the laser only marks it and the app keeps score.
A desk turret you 3D-print and build. It finds balloons and marks each one with a red laser dot. Digital kit from $99. You bring about $180–260 of parts and a Mac with Apple silicon.
Render · the final buildAll black, printed on your own printer or by us. The camera and the laser pointer ride a pan-tilt head on a faceted drum, over a triangular base that holds the electronics.
Digital kit from $99 · Parts about $180–260, not included
What you'll need
The Mac app draws a HUD over the camera feed: detection boxes, the lock, gimbal angles and the score. The screen on the tower shows the camera view over WiFi, and a radar when the turret is idle.
Screen 01 · Mac app
HUDA balloon drifts into view. The box closes on it and reads “Locked on”. When the dot lands, the hit shows as “Marked”.
Screen 02 · Tower
The tower screen's idle radar. It's only for show. The contacts are made up.
SIMThe demos on this page are simulations, not footage from a turret. In the HUD demo a hit pops the balloon for fun. On the real turret, the laser only marks it and the app keeps score.
Three stages. Start the print first: 14 plates, about 41 hours, and it runs on its own.
Stage 01 / 03
Load the 14 ready plates in Bambu Studio: PLA, 0.2 mm layers, about 41 hours and 910 g in all. Order the parts while it prints.
Stage 02 / 03
Two NEMA 17 steppers, two TMC2209 drivers, an Arduino UNO, a small servo for the laser and a 24 V supply. The wiring guides show every connection, and the assembly guide takes you through the build step by step.
Stage 03 / 03
Flash the firmware, plug the UNO into your Mac and open the app. Align the laser with the alignment tool. Then hang a balloon, enable the laser and watch the dot land.
One macOS app for Apple silicon runs the camera, the detector, the tracking and the HUD. Firmware for the UNO and the tower screen does the rest.
MANUAL: aim with the mouse, the keys or the stylus. AUTO: it locks on whatever balloon drifts into view. SCAN: it sweeps ±80° looking for one.
Click a balloon and the head locks on. Lead prediction aims ahead of a moving balloon, and camera-motion compensation tells the balloon's movement apart from the head's own.
Before each frame reaches the detector, the app paints out its own laser dot. It can't chase what it doesn't see. The alignment tool lines the dot up with the crosshair.
A 2.8-inch ESP32 touchscreen shows what the turret sees, live over WiFi. Tap to lock, drag to steer, press MODE, RELEASE or HOME. It can never switch the laser on, and when idle it runs a radar for show.
The HUD calls out each lock and each hit as it happens. Every score is logged, so there's always a number to beat.
With the turret plugged in, the app drives it. Without it, the app runs a demo. Learn the controls before the first plate is done.
This is the Legionary kit, item by item. Recruit includes the first two. Praetorian adds the video course and the build guarantee.
Every printed part of the final v1 build, down to the collet that holds the laser and the servo's finger.
Ready-to-print 3MF plates, sliced and checked for a Bambu Lab P2S, plus a print settings sheet (PLA, 0.2 mm layers).
Every off-the-shelf part with a link to buy it. About $180–260 in total, depending on where you buy.
The wiring guides show every connection, with diagrams. The assembly guide goes step by step, up to the first lock-on.
For the Arduino UNO that drives the two steppers and the laser servo, and for the 2.8-inch tower screen.
The macOS app for Apple silicon: detection, tracking, the HUD, three modes and the score log. It runs a demo until the turret is plugged in.
A YOLO11n detector custom-trained on 275 balloon images. mAP50 0.92, 17 ms per frame on the Mac's CPU.
Measures where the dot lands against the crosshair, in pixels and degrees, and you set the aim point from it.
Plate 01 / 14
Bambu Studio · 3MF
06 · Safety · Lockout
The laser is a Class 2 red presentation pointer under 1 mW. The turret adds interlocks in software and hardware, and the rules below are not optional.
It starts disarmed every time. Disarmed, it scores nothing and the servo never presses the laser's button.
Arming takes the 24 V supply switched on, a deliberate command on the Mac and the A key in the app. It needs all three.
The software looks for faces. While the aim point is near one, no hit is scored and the laser stays off.
Balloons near a person's head are ignored, and so are animals.
SPACE stops all motion. Q sends the head home and makes the turret safe. The board lets go of the laser's button by itself on a stop, when the 24 V goes off, or 5 s after the app goes quiet.
The stylus can lock, steer, release and send the head home. Arming isn't on the screen at all.
Same turret, three ranks. Pick by how much help you want. Your files download the moment you pay.
$99USD
The printed body only. For makers who'll wire their own electronics and write their own code. No app, firmware or guides.
$199USD
The one we recommend. Everything it takes to build and run the turret. You bring the parts, a printer and a Mac.
$499USD
Built and working, or refunded
Watch each stage on video before you do it. If your turret still won't lock on a balloon, you're covered.
New · Pre-order
They ship to you in black PLA, ready to build. The full Praetorian kit downloads the day you order.
You buy the electronics, screws, power supply and laser pointer yourself (about $180–260 from the parts list).
Done for you
$899USD · + shipping, worldwide
Estimated to ship in 3–4 weeks
Pre-order| What you get | Recruit$99 | Legionary$199 | Praetorian$499 |
|---|---|---|---|
| STL files for every printed part | Included | Included | Included |
| 14 Bambu Studio plates and print settings | Included | Included | Included |
| Control app for macOS (Apple silicon) | Not included | Included | Included |
| Firmware for the UNO and the tower screen | Not included | Included | Included |
| Balloon model and laser alignment tool | Not included | Included | Included |
| Written wiring and assembly guides | Not included | Included | Included |
| Parts list with buy links | Not included | Included | Included |
| Free v1 updates | Not included | Included | Included |
| Step-by-step video course | Not included | Not included | Included |
| Fix-or-refund promise | 14 days | 14 days | 14 days |
| Build guarantee | Not included | Not included | 60 days |
PartsThe parts aren't included. Expect about $180–260 in off-the-shelf components, depending on where you buy. You also need a Mac with Apple silicon, basic tools and a 3D printer, unless you pre-order Done for you.
PromiseIf a file won't print, or the software in your kit won't run on a supported Mac, email hello@utinvm.ai within 14 days. We fix it or refund you.
Praetorian doesn't stop at the download. If your turret won't come together, or won't lock on a balloon, we help you finish it. If it still won't work, you get the kit price back.
Get the guided buildGet the complete parts list free. Every motor, board, belt and bearing in one list, so the parts are on their way while the plates print.
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Download the files, load plate 1 and order the parts while it prints. Every kit comes with the 14-day promise, and Praetorian adds the build guarantee.
