What you’re building
The handle and the middle of the head are one piece of 2x4, 17 inches long. The top 5 inches stay full width; the rest is cut down to a 1½-inch-square handle. Two 5-inch cheeks glue onto either side of the full-width section, so the handle runs up through the center of a head that is 5 inches long, 4½ thick, and 3½ tall. Nothing is joined end to end, so there’s no joint to fail when you swing it. The striking faces are the end grain of the 2x4, which takes hits without crushing.
It weighs a little over a pound in dry SPF, which is right for chisel work and knocking joints together. For a heavier assembly mallet, make the head pieces 6 inches instead of 5.
Pick the board
This project uses the best 27 inches of a board, so it’s a good use of the clean end of a 2x4 you bought for something else. Avoid knots in the head pieces; a knot on a striking face will split out. The long piece needs straight grain running its full 17 inches, since the handle is the thin part and any grain run-out there is where it will break.
Cut
Cut the 17-inch piece first, then the two 5-inch cheeks. Cut the cheeks one after the other and check them against each other; if their lengths match exactly, the head will be flush without much sanding.
Shape the handle
Mark a line across the long piece 5 inches from one end. That end stays full width and becomes the middle layer of the head. Below the line, draw the handle: 1½ inches wide, centered on the 3½-inch face, running to the other end. Cut the two long rip lines with a jigsaw or a hand saw, stopping at the 5-inch mark, then cut in from each edge along the mark to free the offcuts. If your rip wanders, that’s fine; the handle gets rounded anyway. Rasp or sand the four long edges of the handle until it’s comfortable. An octagon is enough; a full round is nicer.
Glue up the head
Dry-fit the cheeks against the head core and check the ends are flush. Spread glue on both faces of the core’s head section, press the cheeks on, and clamp across the thickness with two clamps, one near each end. Wipe the squeeze-out. If you’re worried about the glue joint, drive two 2½-inch screws through each cheek into the core, countersunk and staggered so they don’t hit each other. Leave it clamped overnight.
Finish
Sand the striking faces flat and the head edges lightly round; a sharp corner will chip on the first miss. Sand the handle to 220. Two coats of boiled linseed oil, wiped on and wiped off, is the traditional finish and the right one here. Nothing slippery.
If something goes wrong
- Cheeks slid during clamping. Common. Sand or plane the ends flush once dry; a little misalignment doesn’t affect the mallet.
- Handle feels too square. Keep going with the rasp until the corners are gone. A 1½-inch octagon suits most hands.
- A striking face dents. Normal. It’s a mallet.