I use the same system Kenny has on his build along with a pattern , only i have a 2hp router mounted on a section of one of my work benches and use a much bigger flush cut bit.
Using a router table is much easier for me to keep the cut edge 90 degrees than free handing with a 2" flush cutter, but you need a nice flat off fall table.
But it can be done ok with a steady hand like Kenny's photos.