Joinery layout. I'm laying out leg mortises. In this case, this face of the leg is rounded so I'll use stepped mortises. First I lay out a shallow mortise, I call it a socket, that gives the ends of the rungs a flat place to land. Then there's a smaller deeper mortise that will eventually accept a loose tenon.

The stretcher joinery. I use a stepped mortise to join the stretchers of the chair since the face of the leg is rounded. This technique creates a shallow, flat platform on the curved surface of the leg for the end of the stretcher. This drawing was first published in Furniture: 102 Contemporary Furniture Designs. Click to enlarge the drawing.

Mortising. I cut the mortises with a JDS Multi-Router. To save time, I set up 2 identical routers with 2 different bits to create the stepped-mortises: one at 5/8" diameter to cut the shallow mortise or socket and another at 5/16" diameter to cut the deeper mortise.

The rungs. All rungs are milled slightly oversized in both width and thickness and given a centered mortise.

Fitting the rungs. Now I fit the side rungs into the shallow mortises or sockets in the legs.

Fitting begins with shaping the top of the rung to match its socket and adjusting the thickness to tight. Here I butt the rung up against the top of the socket and mark around the bottom of the rung on the leg. This outline shows me where the rung is larger than the socket and where I need to remove material. I use the little block plane and sand to fit. 

Make an arm rest. The arms are just like the rungs, but have an additional side piece to create an arm rest.

Prior to fitting each arm, I glue these 2 pieces together. Both parts were side by side in the same board. Its thickness gives me the width of my rung. I rip off the rung, then re-saw the offcut to get the thinner wing. If all goes well, the finished arm looks as if it were shaped from a single piece.