I made the legs from laminated 4/4 stock, and since I was gluing the legs, I took the opportunity to Leave one piece shorter. The joinery to the desk calls for a large rabbet at the top of the legs, and leaving that area as 4/4 simplified that task. 

With the legs glued up, the edges can be cleaned up at the jointer.

The legs were then cut to width at the table saw.    

Leaving the top of the legs at 4/4 saves a lot of time, but the shoulder still needed to be squared up. This was done with a flat bottom blade and my cross cut sled.

Final cleanup of the shoulder was done by hand. 

Cutting the legs to length had to be done in two steps. First, the length below the shoulder was cut creating the height that the desktop assembly will sit on. 

Next, the upper section was cut to the same height as the upper desktop case assembly. 

With both legs clamped together, the center line for the stretcher can be marked. 

The center line is then transferred to the inside of the legs. 

The center stretcher is cut to length at the table saw. 

The center line is then transferred to the stretcher. 

The joinery will be double loose tenons. I'm going with 3/8" thick X 1 1/2" wide tenons. The mortises are cut at my shop made horizontal slot mortiser. Operations like this are what make this tool so useful. The size, thickness, and depth of the mortises is all configurable with this tool. 

A closeup of the mortise configuration. 

With the joinery cut, I can move on to shaping the legs. This starts with a template made out of 1/4" plywood. The center line for the joinery, as well as a buffer on either side (representing the stretcher width) is marked on the template, and then a curve is drawn on either side. 

I am careful to keep the curve from cutting into the buffer I marked out earlier. This is the area where the stretcher will meet the legs and cannot have a curve. 

Once the curves are drawn, the template is cut at the bandsaw and then cleaned up by hand. 

The template is traced onto both legs. It is important that the template is flipped for the second leg. Each leg should appear to be a mirror image of the other. 

The legs are rough cut at the bandsaw being careful to stay outside the line. 

The legs are cleaned up first at the spindle sander. 

Final cleanup is done by hand. 

The template for the center stretcher is marked out in a similar way to the leg templates except only one side needs to be cut. The template will be flipped over to mark the second side of the stretcher. 

The template is cut out at the bandsaw and cleaned up by hand. 

The curves are then marked on the stretcher. 

The stretcher is rough cut at the bandsaw and cleaned up at the spindle sander. 

With the shaping done, the leg assembly can be glued up. 

After glue up, the legs receive a roundover on all sides. There will be a small support piece added to the inside of the legs. I make sure not to round this area over. 

This small support piece will be the piece that locks the legs in when they are bolted on to the case. Each support piece has a mortise centered in the top that will be used later. That center line is used to align the piece to the leg. 

The excess is trimmed at the bandsaw. 

The supports are flushed up at the router table. 

The edge treatments are blended by hand. 

The upper desktop case assembly is flipped upside down on the workbench so that the knock down joinery can be marked. The center lines from the support piece mortises are marked on the bottom of the assembly. 

Matching mortises can then be cut into the bottom of the assembly. These mortises are slightly elongated to allow for seasonal wood movement. 

A template is used to mark out the bolt holes for the legs. 

The upper desktop case assembly is disassembled and the bolt holes are drilled for both legs. 

The legs receive threaded inserts. 

The rear bolt holes are elongated to allow for seasonal wood movement. 

The legs can then be bolted on.