Too bad silencers are all but illegal. Sub sonic rounds are pretty quiet though.
Easy and cheap to make and then throw them in the trash.
You are misinformed. Silencers are not illegal if you pay the tax stamp on them. If you can own a gun you can pay the taxes for one and you are 100% legal.
In fact, before the 1930s when they passed the tax on silencers, most people in urban areas used them regularly in order to target practice or hunt without bothering their neighbors. Hardly anyone used them for illegal snipings.