The toolhead fan duct has mounting holes to mount the Fystec PIS (portable input shaper). I had an ADXL345 soldered and wired for a different printer and didn't want to spend the $20 or so on Amazon for something that, as far as I can tell, does the exact same thing. This adapter allows you to use an ADXL345 (specifically, the kind shown in the image) to the toolhead.

Requires 2x M3 heatset inserts. The ones purchased from the printer BOM are recommended (3x4x5).

Will also required 4x M3x4-8mm screws. I used 4x M3x6 as those were also spares from the printer build.