I think I ended up doing 4 or 5 before I got one I was reasonably happy with. To get the overall shape (not what you're asking) I used the paper template from the plans to draw the shape on the
block(s) of wood - I used cherry. Then I tipped a scroll saw table to aproximate the drawn cut line and cut the wood to approximate the shape. Cleaned it up on a belt sander mounted sideways on a makeshift table. I launched a few from the beltsander - not good for the fingers. To start the recess I redrew lines where necessary and using a dovetail saw or pull saw cut the lines that represented the termination of the wood I wanted to remove. That gave me a depth guide and made it easier to pare away unwanted wood with a chisel or a small plane without slicing off wood I wanted to keep.

You may be able to cut the top lines by tipping a tablesaw blade (5 degrees?) and doing those cuts before any other shaping. You might also consider an easier to carve wood if you're not already using one like basswood. Finally Mike's suggestion about skipping the recess was offered to me by someone else. I think that would be a fine alternative, one you may want to consider if you reach your own personal limit on number of attempts.