I designed some mounts for kusba adxl345 usb pcb by maker panda for my Elegoo Neptune 3 Pro. 

For klipper resonance compensation/measuring: https://www.klipper3d.org/Measuring_Resonances.html

Link to a good (german) documentation:
https://book.cryd.de/books/klipper/page/youtube-adxl345-einrichten

Link to the kusba adxl345 usb PCB at AliExpress:
https://de.aliexpress.com/item/1005005182131890.html

You will need:

• 1x or 2x kusba adxl345 usb pcbs (when you use 2, you don't need to switch the pcb/mounts)
• 1x M3 12mm Screw, Nut (& Washer optional)
• 2x M3 6mm Screw, Nut (& Washer optional)
• 2x M3 10mm Scew & Nut
• 2x M3 8mm Screw, Nut (& Washer optional)

See Pictures for Details.

I also added the FreeCad Files (i used Version 0.21.1) if you need any customizations.

In case you use 2 adxl345 chips, here is my printer.cfg snippet:

[mcu adxl_hotend]
# Hotend (X Axis)
# find your correct device id's with "ls /dev/serial/by-id/*" on your RasPi
serial: /dev/serial/by-id/usb-Klipper_rp2040_E6624C9027674638-if00
[mcu adxl_bed]
Printbed (Y Axis)
find your correct device id's with "ls /dev/serial/by-id/*" on your RasPi
serial: /dev/serial/by-id/usb-Klipper_rp2040_E6624C9027418D2F-if00
[adxl345 hotend]
cs_pin: adxl_hotend:gpio1
spi_software_sclk_pin: adxl_hotend:gpio2
spi_software_mosi_pin: adxl_hotend:gpio3
spi_software_miso_pin: adxl_hotend:gpio0
[adxl345 bed]
cs_pin: adxl_bed:gpio1
spi_software_sclk_pin: adxl_bed:gpio2
spi_software_mosi_pin: adxl_bed:gpio3
spi_software_miso_pin: adxl_bed:gpio0
[resonance_tester]
accel_chip_x: adxl345 hotend
accel_chip_y: adxl345 bed
probe_points:
   120,120,20

After restart, you should have 2 new MCUs ("mcu adxl_bed" and "mcu adxl_hotend") in the "MACHINE" menu.

You now can use the following Console Commands:
TEST_RESONANCES chips="hotend, bed" axis=X
and
TEST_RESONANCES chips="hotend, bed" axis=Y
to measure resonances on the two axis. Follow the official documentation from here: https://www.klipper3d.org/Measuring_Resonances.html