LOL mine is wayyyy ghetto but it works and didn't cost me anything so who cares. I actually used 2 solo cups, a coffee filter and a couple air fittings I had laying around the shop. I reduce the line pressure to about 2lbs. and hook to my shop compressor. One solo cup has pin holes punched in the bottom and the filter taped over the holes on the outside. The other cup has a hole at the base that is fitted with the fitting. The filtered cup nests inside the fitting cup and is taped together for a decent seal.
Basically I mocked it up while studying the idea of making one, and it worked, but Ive been so busy I haven't had time to make a nicer one.