FTN4 is the best printed suppressor out there. There are options for 22lr, 556, 308, 9mm, and 45. They need reinforcement, either an aluminum tube or a carbon fiber sleeve. With suppressors tax dropping next year, someone may come up with a better design eventually. However, the FTN series of suppressors is quite robust and can handle FA rates of fire, especially when it's made of PA6-CF or even better, PPA-CF.