I'm a private investor, who applies active trading strategies since 2007. While I'm not a "quant" trader in a classical sense, my engineering background enables me to use quantitative techniques in my discretionary swing trading approach.
My strategy has been inspired by various traders: Alexander Elder (channel techniques), Adam Grimes (focus on buying/selling pressure) and Victor Niederhoffer ("you have to test everything").
Holding periods of a few days to weeks requires constant price monitoring, which could be challenging as a part time trader. However, for me this is easily possible since I'm located in Germany and US markets are open from 3:30 until 10pm local time.
Since my trading approach has been working very well right from the beginning, I was asked in 2009 to be one of the first model managers on the new Covestor model subscription platform. As of December 2012, the "Technical Swing" strategy returned over 85% since inception while the S&P 500 lost 1% during the same time. Of course, I still keep improving the approach to adopt to new market conditions.