Measuring beyond (more accurately) than 1/64th or .0156 (1 div by 64) with a tape measure is almost out of the question in the home garage. How are you going to incorporate a "steel rule" (piece of steel graduated in decimal and inches) into the measurement??. 1/64th is pretty small even on one of these "steel rules" ( no er attached).
The distinction of scales, rules and rulers was taught in about 7th grade drafting. The "whack" method with each produced lifetime memories.
Here are a couple of good Lufkin tapes. 1/16 and 1/32. Just use a cheap calculator for any conversions. Make a sketch and do the math ahead of time.