I drawed it first on sketchup some time ago. It was time for action, I grabbed an old broom, machined some aluminum, grinded an allen wrench and here it is the marking gauge. It passed the exam, accurate enough for me .
Looks great, and I like the idea of a gauge with a handle like that. My only concern is that every other gauge has a flat surface to ride on the edge of a bard, to ensure that it stays perpendicular to the edge, otherwise the distance changes.
Thanks for the kind comments. I'm not sure I can claim it is my own design as it is very similar to a fly cutter, but the broom handle is an idea of my own . I was concerned too about the accuracy as it hasn't a flat surface. I thought on sanding a flat side but I first made a test of accuracy. I drew three 50cm (20") lines. And I took my caliper:
at the top
at the bottom
Believe me or not . It would be ridiculous to say that it can handle the 1/100mm (0.0004" !) as it is difficult to use the caliper but it proves that it is rather accurate. Or that I'm very lucky…