How to a make marking tool. 2 in 1 wood tool. Beam compass tool and marking gauge. Simple, homemade. You can mark to cut wood in the middle. You can draw a parallel line. You can draw perfect circles using this caliper.
Making Video :
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Did you see this ? Wooden Compass Making
I also added a foot pedal. The foot pedal was extremely handy. Table saw, router and jig saw is very easy to operate.