I sat down today with some graph paper and tried to get a concrete drawing for the mallet. After a little fooling around, I was happy with one that I came up with, then drew it up in Inkscape:

The planned dimensions are 5″ wide and 10″ long. The striking faces are about two and a half inches long.

The mallet will be roughly 2 5/8″ deep. I don’t know for sure, because I’m too lazy to check the exact width of my newly-milled piece of lumber. The idea here is to laminate the head, and at the same time, eliminate the need for making a complicated angled mortise for the handle (as well as save a lot of money on lumber). We’ll see how this works out. In any case, the striking faces should be roughly square.

Though the drawing’s handle is rather angular-looking, it will be oval in the final product.

One very amusing thing about the design is that all fits in actual size on a printed sheet of 8.5×11″ paper. Useful, too, I guess.

[Update: Here are the SVG plans for the mallet.] sigh