I just made these https://www.thingiverse.com/thing:2830677. My comments are in Thingiverse. Needless to say I was sceptical but proved wrong, they have really quietened down the printer, more so for the lower frequency sounds. The higher pitched sounds remain much the same.
You need to make four of each part and assembly is a little tricky - turn the inside part sideways, insert into the outer and twist.
Very useful addition to the Snapmaker and highly recommended.