I use this on my new Ultimaker Original Plus, to significantly reduce noise level of the machine.

You might also want to print some feet as well, while you have the flex material loaded anyway. Like Daids: https://www.youmagine.com/designs/ultimaker-noise-reduction-feet or whichever you like best.

Settings to start with:

I used clear Ninjaflex on UMO+

Nozzle temp. 242°C
Bed temp.    50°C
Fan      off

Print speed  25 mm/s (constant for everything incl. infill)
Gap speed   250 mm/s
Retraction   off
Layer hight 0.15 mm
Wall thickness   1 mm (top, bottom, sides)
Infill      40%
Flowrate    130%

Print one at a time, no need for additional plattform adhesion, or support.

The feeder damper should be oriented 'feeder side' (flat side) down. The inner back wall is slightly angled to print nicely without support.

Put the zip-ties in a loop through the rectangular holes of the pegs and through the middle wall. For dual extruder setup / back left extruder slot, use only the top row to fasten. Otherwise you will interfere with the Z-endstop switch!

Happy printing everyone!