Need a single tool to accomplish many tasks? That's what the 3-in-1 Marking Tool was designed for. With this single tool, you can make perfect circles, find the centers of boards, and measure short distances.

Step 1: Materials

2x 1" x 6 1/2" x 3/4 wood of your choice.
2x 1" Brad Nails
1x 5/16 nut and bolt
1/4" Dowel
Plastic Ruler
Epoxy
Wood Glue

As far as tools go, you will need a minimum of:

Drill
Table saw
Miter saw (or another crosscut saw)

Step 2: The Compass

First, drill a hole through both blanks about 1/2" from the top. This is what the bolt goes through, so make it just large enough for the thread to go through. Then countersink a hole for the nut to go through on one of the pieces. Place the nut in the hole and glue if needed. In my case, friction was enough to hold the nut in. I made a knob for the bolt by drilling through a scrap of wood with a hole saw, epoxying the bolt into the hole, and cleaning the knob up on the drill, but this is completely optional. Finally, drill holes in the center of the bottoms of the blanks and place the brads (after removing the heads) in the holes with epoxy.

Step 3: The Ruler

Using a utility knife, score a line along the side of the plastic ruler. Then, snap the ruler along the score line. Make sure that you take off the excess from the start of the ruler so that it starts from the very front. Then, with a table saw or router, cut a groove the same dimensions as the ruler along the blank with the nut in it, making sure that the nut is clear of the groove. At this point, I suggest you sand the tool because after attaching the ruler, sanding will be difficult. Then, using epoxy or another fixative, secure the ruler.

Step 4: The Center Finder

Mark on the blank without the nut 1", 3" and 5" from the bottom, being sure to be as precise as possible. Then, drill holes just large enough for the dowels for the first and last and one just large enough for the pencil for the middle hole. Glue the dowels in place with wood glue.