3D printed magnetic tape measure holder. 
 
3D printed parts only version requires magnets (affiliate link), 11" zip tie and HF "Pittsburg" tape measure. 
Select the 3D printed parts + magnets if you already have the correct Harbor Freight tape measure. 
Fully assembled option is pretty self explanatory!
 
 
Full write up and more info can be found here: https://www.instructables.com/A-Better-Firewood-Measuring-Stick-And-Its-Not-a-St/