As shown in the sample picture (not the one I built), a marking knife is a layout tool. It's for making lines to follow to do mortises or dovetails or any other task calling for a thin line where a thicker pencil line just won't do.

Step 1: DID I REALLY NEED ONE?

Nope. I didn't really need one. I just wanted it. My Little Shop called out to me and said, "Feed Me, Jarfold!"

I've used utility knives, x-acto knives, even pen knives and they all work fine, but I was cleaning out my desk drawer and came across a pen I was just about to throw out.

Step 2: A PEN AND PEN KNIFE

I was about to toss them both when it hit me like a total eclipse of the sun.

Step 3: FINE SANDPAPER

I sanded off all the advertising on the pen.

Step 4: BAMBOO SKEWER

How will I secure the blade? A bamboo kitchen skewer was just the right size to fit in the pen. I cut it to size on my trusty dowel cutting jig.

Step 5: GRINDING

I ground down the blade to a really sharp edge and then ground down the tine. Then I took my Dollar Store nippers and cut the blade. Yes, I set it free.

Step 6: SECURING THE BLADE

I split the skewer and slipped in the tine. Then slipped it into the pen. When the skewer reached the split part being wider, it fit snugly into the opening, holding the blade tightly.

Who remembers School House Rock? Everybody sing: Lolly, lolly lolly get your adverbs here....

Step 7: TESTING THE CUT

It works like a charm.

Step 8: CAP IT!

And the cap even fits. Now I have a marking knife. My Little Shop is happy.

Step 9: PROLOGUE

Yes, those wires nippers cost me a dollar at the Dollar Store. Yes, this marking knife was made from things I was going to toss. I've even named the knife Audrey III.

Hope you enjoyed. Feel free to ask questions and make comments.

KJ

Yes, I do name my tools.

In my shop I got a name for saw and hammer and plier

The saw is Tess, the hammer's Joe and Glumdalclitch is the plier.

the plier

and Glumdalclitch is the plier.....