BIQU · Laser, CNC & Maker Add-ons
BIQU BMCU-370 review (preview): open-source four-colour printing for Bambu A1 and P1
An open-source, four-channel AMS Lite alternative for Bambu Lab A1, A1 mini and P1, $125.99 assembled. Cheap and capable, but firmware updates could break it and there is no RFID.
Good
Best for Tinkerers with a Bambu A1 or P1 who want multicolour on a budget
List price$125.99
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Preview review. Compiled from manufacturer specifications and published information. We will update the scores after hands-on testing.
Our verdict
The BMCU-370 brings four-colour printing to Bambu A1 and P1 printers for less than an AMS Lite, using a stronger 370 motor and Hall-effect sensing. Owners mostly report it works, but some had to make the printer think it was a full AMS, one saw random disconnects, and 3DBite warns a Bambu firmware update could block it. Buy it if you enjoy tinkering and accept that risk.
What we like
- Four-filament automatic switching for A1, A1 mini, P1P and P1S
- 370 motor with Hall sensor: more torque, quieter, better filament detection
- Open source and repairable
- Cheaper than official AMS units; DIY kit $88.99
- Detects transparent filament (photoelectric sensing)
What could be better
- A Bambu firmware update could stop it working; community support only
- No RFID: filament details entered by hand in Bambu Studio
- Some owners had to set the printer to “AMS” instead of “AMS Lite”
- Reports of random disconnects and getting stuck at 99%
- May affect your Bambu warranty
Score breakdown
Overall = 35% Power and output + 25% Build and results + 20% Setup and ease of use + 20% Value. How we test
What is it?
The BMCU (Bambu Multi-Color Unit) started as a community open-source project to feed up to four filaments into Bambu Lab printers that lack an AMS. BIQU’s BMCU-370 is a commercial version with a stronger 370 motor and Hall-effect sensors.
It costs $125.99 assembled or $88.99 as a DIY kit on BIQU’s store.
A note on evidence
We found no long-form independent print test. This preview draws on 3DBite’s detailed comparison and risk analysis, 3Druck’s coverage, and owner reports. Treat it accordingly.
What it does well
- Four channels with automatic filament changes during a print.
- The 370 motor gives more torque and quieter feeding than smaller-motor BMCU builds.
- Photoelectric detection senses transparent filament, which microswitch sensors can miss.
- It’s open source, so parts can be repaired or replaced.
Problems owners report
From 3DBite and BIQU’s product page:
- Some A1 owners had to tell the printer it was connected to a full AMS rather than an AMS Lite.
- One channel can be noisier than the others; a channel can show filament when there is none; and a print can stick at 99% because the unit can’t retract.
- One builder saw the printer randomly lose connection to the unit, needing a power cycle.
- No RFID, so you enter filament types and colours by hand.
The firmware risk
This is the big one. The BMCU has survived two Bambu firmware updates, but 3DBite notes the community warns Bambu could block it, and its main firmware maintainer is moving to Klipper printers. Some owners freeze their printer firmware to stay safe. It may also affect warranty claims.
Who should not buy it
- Anyone who wants plug-and-play reliability: buy an AMS Lite or AMS 2 Pro.
- Anyone who keeps firmware updated automatically.
Final thoughts
The BMCU-370 is a clever, cheap way into multicolour on Bambu printers, but you’re buying into a community project with real risks.
Sources
Full specifications
| Channels | 4 |
|---|---|
| Motor | 370 motor, Hall-effect version |
| Compatible | Bambu Lab A1, A1 mini, P1P, P1S |
| Filament detection | Photoelectric (works with transparent filament) |
| RFID | No |
| Price | Assembled $125.99 · DIY kit $88.99 |
| Released | 2025 |
Ready to buy?
BIQU BMCU-370
List price $125.99. Prices change often, so check the current deal.
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