Always wanted a suppressor for your pistol but don’t want to spend too much cash? Well you can make one out of an oil filter. For $20 you can buy an adapter, which needs to be registered with the ATF, and make your own suppressor. The automotive oil filter works as a removable expansion chamber. This seems like a cool toy for the novelty factor, but I doubt you’ll see the SEALs using this anytime soon. Again, these must be registered and you have to pay a tax stamp to use these just like with standard suppressors.