There are quite a few kinds of DIY suppressors that can be built with a few basic tools. I've talked about the oil filter adapter on Amazon, but another popular model is the Maglight style suppressor. Just to be clear making your own silencer, without the proper paperwork, is highly illegal and potentially dangerous. I'm not a lawyer so be sure to do your own research.
The Maglight style of suppressor requires a bit of work and a handful of parts. The majority of work can be accomplished with some freeze plugs and a drill press but it is a bit of a pain in the ass. SD Tactical has put together a super long informative vid on the process works below as well as a kit for purchase. Just a heads up, the actual firing happens at about 15:20 and the purchase info is shown at 19:40.
I'm not sure if SD Tactical hasn't figured out how to do ecommerce or they are just trying to be secretive in the selling of their kit. Overall, the cost seems fairly reasonable, but don't forget the tax stamp from the ATF. For more info visit SD Tactical or email firstname.lastname@example.org