Have you ever tried to use a plug cutter in a handheld drill? The cutter usually dances all over the top of the workpiece. If you don't have a drill press to keep the cutter steady, here's a solution.
Steady Plug Cutter

In a piece of 12 " or thicker scrap plywood, drill a series of holes just big enough for the plug cutter to slip into without binding. Position the plywood template on top of the stock you want to take some plugs from and securely clamp the plywood and the stock to a benchtop.

Now, insert your plug cutter into the guide holes and drill into the plug stock. The holes in the plywood will keep the plug cutter steady enough as you drill to give you good results.
—Jack Schmittel, Durango, Colo.