Cutting dados and tenons require precise tolerances. This handheld router is easy to make and provides a consistent depth of cut and better feel than a powered router.
Start with a 3 x 1 piece of scrap wood and a sharp chisel. Select a drill bit that is slightly more narrow than the chisel and drill halfway into the center of the wood at a 35 to 45 degree angle.
Use a hammer to drive your chisel (bevel down) through the angled hole, until it just breaks out through the other side. This handheld router will work best with a recess that's already started and is great for fine tuning the depth.
Paul Sellers' Poor Man's Hand Router |Paul Sellers