Simple but effective marking gauge
It's tough to beat a marking gauge for creating crisp, repeatable layout lines. Consisting of a beam, a sliding fence held in place by a small wedge, and a scribing point, this time-tested tool sets up quickly. To learn how to use it, click on the link below.
To build one, start by cutting the beam to the size shown in the drawing, below. Then, to create the thumbnail profile on one edge, chuck a 1/2" round-over bit in your table-mounted router, and rout the partial round-over using just a portion of the bit. Now drill a hole near one end to receive a 6d finish nail. Insert the nail, allowing the point to project 1/8". Cut off the head leaving 1/8" exposed on that end, as well. Then sharpen both ends to create the scribing pin.
Make the wedge by tracing the full-size pattern shown below onto a piece of 5/8x4x2" stock, running the wood's grain lengthwise. (An oversize piece is safer to handle as you shape the wedge.) Bandsaw the wedge to shape, and then sand it smooth so it slides easily against the beam and fence.
To create the fence, first cut it to shape using the full-size pattern as a guide. Next, bore a 3/4" hole through the fence where dimensioned. Using chisels, a flat file, and a round file, expand the hole, and shape it into an opening that fits the beam and wedge. Note that one side of the opening tapers to match the wedge. Be sure to test-fit the beam and wedge periodically as you shape the opening.
To protect the marking gauge, top it off with a couple of coats of oil finish.