BambuLab A1 Springy Plotter Adapter

Transform your BambuLab A1 into a capable plotter with this lightweight, minimalist pen adapter. Designed for simplicity and versatility, this adapter supports a wide range of pens—both round and square—up to 16.5mm in diameter. Installation is quick and tool-friendly, requiring only a single M4 screw to secure the pen in place.

A key feature is the integrated spring-loaded pen holder, allowing for consistent pressure during plotting or forgiving minor calibration inaccuracies. This ensures smooth and clean lines, even on uneven surfaces or during quick swaps between pens.

Unlike more complex alternatives, this adapter boasts a streamlined design that avoids the need for excessive screws, brackets, or specialty parts. Whether you're just getting started with CNC plotting or you're looking for a reliable upgrade, this adapter balances function, form, and ease of use.

The adapter clamps on to the filament input port on the A1 for a secure fit. This has the bonus to eject the adapter if the pen is pushed too hard and not damage the build plate &/ the pen. 

Supports both square and round pens, included a round only for those who are not interested in square pens.

I recommend that the print lays flat on the side as illustrated in the image for maximum strenght of the spring.

The fastening holes are undersized by purpose to 3.9mm in diameter to make the screw tap the hole.

My adapter is printed using PETG, I have not tested PLA. No supports needed.

Specifications

• Compatibility: BambuLab A1
• Pen Support: Round or square pens up to ~16mm diameter
• Fastening Method:
  • Clamp ring/square around the AMS 4 input as shown in image (red)
  • Requires one M4 screw (suggested length 10–16mm)
  • Optional second M4 hole for extra stability
• Mechanism:
  • Spring-loaded pen holder for pressure compensation and tolerance to calibration offsets
• Design Goals:
  • Minimalist construction
  • No complex hardware or assembly
  • Easy to print and mount