Or almost 
Short answer:
Print these: HULA Anti-Vibration Feet for 3D Printers by thrutheframe - MakerWorld, equip with the appropriate bearings, install and send a few more than very well deserved Boost’s to @thrutheframe like I did. They do indeed work 
Long answer:
When I stumbled across this thread: Anti-vibration feet and misconceptions (Vibration Tip), I remembered my past studies in Sound and Vibration and enjoyed being able to share some background 
However, I also wanted to play around a bit. In particular looking at the difference between Vibration Isolators and Vibration Absorbers. So as a quick experiment and - not being much of a designer - being able to try out a contribution to MakerWorld, I made these: Anti-Vibration Pad Mk I by EnoTheThracian - MakerWorld. DO NOT print these for anything permanent. Unless of course you do just want to play around a bit. You can indeed make a true vibration absorber that way.
I had planned to take that work a bit further, but then ran into long lasting issues with my X1C. They were only solved by a replacement machine. But that is another long and painful story of endorphine withdrawal (fortunately almost fully and completely over now).
When it transpired that a replacement machine would come soon, I stumbled across the HULA … and was electrified 
. Extremely well thought out, just as complex as needed with every likely overcomplication removed! Kudos to @thrutheframe for this work . I would not have gotten anywhere near that 
.
Even though they are quite effective, there may be further tweaking opportunities:
- I slightly changed the print profile to use a PLA support interface for the PETG parts with a 0mm z-clearance. Worked excellent No further smoothing work required .
- I am not quite sure about the spring stiffness k. It is given as as being identical in X/Y and Z. In my experiments, I measured rather different natural frequencies. I think it was 12Hz in both X and Y but 8Hz in Z. However, I only used my phone, it was a while ago and I have not had the time to dive into calculations on the HULA spring. I would not be surprised if @thrutheframe had done that very thoroughly though and I will just have to adjust my gut feeling.
- Furthermore, there’s a tiny little play between the spring and the casing, leading to the spring not affecting small movements. Tighter spacing however would make assembly a right pain. Nevertheless, a connection between the case, the spring and the central block may make the springs effective right from 0. But again, @thutheframe has probably already thought about that
- In my prints, I also eliminated the Z-cushion (by only having a 2 layer TPU cushion) as I wanted to limit X/Y vibration but was not bothered by the secondary Z movement (since it is a result of an out-of-plane X/Y acceleration reaction and will already be affected by X/Y decoupling).
=> I’d love to, at some point in the future, have a the chance to calculate the spring stiffnesses to use 8 HULA’s with modified springs (4 with ~5% increased k, 4 with ~5% decreased k) in order turn those Vibration Isolators into a single Vibration Absorber. And maybe remodel the height a bit to limit the printers height when sitting on it. Alas, it’ll be (quite) a while. My X1C failure led to 5 months of print idea backlog growing into a mountain. And a lot of that requires my extremely limited design capabilities… But maybe @thrutheframe or another fellow enjoys the experiment?
And a final, only moderately related thing I had wanted to say for a couple of weeks: @Olias : Many thanks for your initial Onshape recommendation in some post in 2023 . Starting to learn it by doing now. Already further in my design capabilities after a handful of hours than after years of bumbling around with FreeCAD .