This has been redesigned to better stay on the hammer cord and use the cord to keep the silencer horizontal.  It's printed in 2 pieces with the cord-stay designed to remain on the cord when the silencer ring is removed.

The cord-stay is a bit snug on the hammer cord I have which is about 3/32" (2.4mm) diameter.

I made it out of PLA; you may want to consider other outdoor appropriate materials.

Print the cord-stay upside down to eliminate the need for bridge material.