Paul Sellers brings this great video for how to make a marking gauge for under $1. It is simple to make, yet brings a high degree of precision for marking dovetails and dado depths.
Tools needed:
saw
drill
screwdriver
sandpaper
file
chisel
Materials:
1 steel flat-head screw 1 to 2″ long. Preferably slotted, rather than Phillips or square drive.
1 scrap of wood roughly the size of a can of tuna-fish.
Watch Paul show you how its done without spending money on fancier marking gauges, beading tool, or scratch stock. The simplicity is awesome, and so is the realization that this can be fine tuned more than any of the expensive marking gauges available for purchase.
And here is a short follow-up video where Paul addresses even more that can be done with his simple beading tool.
It is easy to save money in the workshop by making your own tools. This is especially true when the tools are simple in design. This simple marking gauge is worth checking out.
I think that upgrading the needle to a nail filed to a cutter blade shape then heat treated might be a good idea, but maybe this needle works well enough as it is.