In the following photos I will demonstrate how I made one part of a molding profile on a piece of sample window casing using 19th century hand planes. I am using a scrap piece of basswood approximately 4 inches wide and am working in the wood shop at The Landing, a living history museum located in Shakopee, MN.
I began by adding beads along both edges of the casing using snipe's bills and a #2 round (a side bead plane would work just as well). For the next step I will add a shallow, rounded groove down the middle of the casing. To start I lay out a small groove which will serve as a guide for a molding plane. Here I am using an adjustable plow plane with a movable fence and depth stop which allow me to place a groove of any depth anywhere on the face of the stock.
The chamfers guide the #5 round along the length of the casing. I plane the entire length until the groove from the plow plane has disappeared and I have one, full-width shaving.
After a bit of refining and smoothing you are done. You can continue and use other planes to add more complexity to the molding, including hollows to round off the sharp corners.