I used to do this until I realized how dangerous it is. I still find old helmets and paint them for fun. but would not wear them for anything. I have a friend who died trying to 'look cool'. it's just not worth it. Bell makes some cool 'vintage looking' 3/4 helmets.
I recommend wearing a full face helmet anytime you get on the freeway. and a modern 3/4 is cool for gettin groceries. puddin basins are pointless and look stupid, IMHO. that being said my buddy wears one. I wish he wouldn't. cuz I'm not gonna hang out with him if he's a drooling mess.
but the impact foam degrades, breaks down with time and becomes useless. leaving you unprotected. and do you trust yourself to replace it and create decent head protection. you can't just throw packing peanuts in there. it's what keeps you from being DEAD or RETARDED.
don't do it. stay alive.