This is a very simple, super fast to print z-axis vibration damper for the original Prusa MK3.
On the MK2, the Z-top parts had a hole for the Z-rods. For my MK2S I already designed a while ago some z-rod
The new Z-top parts for the MK3 are closed at the top. Still the hole for the z-rods on the top parts are much larger than the Z-rods: this is as per design and should allow the rods to wobble a bit. The general accepted advice is to give the z-rods some space to do so. Great, however on my MK3 at certain z-heights, the rods touch the z-top parts and generate a rattling noise.
Hence I quickly made a small damper that you can slide over the top of z-rods to avoid the vibration. The walls are very thin (only one perimeter) and still allow for a lot of room for the z-rods to wobble. The top of the damper is only 0,2 mm such that it does not touch the z-axis top part. Print this with TPU or TPE. The noise is gone and I do not see any effects on print quality.
Update 26-05-2018, revision 1: increased the single wall from 0.42 till 0.45 mm such that 'detect thin walls' do not have to be set (depending on your slicer and settings)