Understanding Proper Scaling for 3d Export dimensions Hey im using the latest version of blender as of march 2018

I made a custom wall plate for a relative to 3d print. I made sure to set units to "Imperial" and "Inches" as i needed a piece that is 1.5" square. here is a picture of my current settings


Now here is my 3d view port


As you can see i have my scale set to 1.5" but the problem happened when i shared the file (a .STL) with my relative and they printed it it came out as 1mm wallplate, so if their is anyway to tell blender or the exported stl to be in inches that would be great! thanks guys
When you exported to .STL, did you check the box next to "Scene Unit"? (Find this on the lower left hand side when you attempt the export).



When a model is 3D printed, it has to be converted to GCode using some other software. Was this software configured correctly to handle inches? 

My advice: save yourself the hassle and just work in millimeters and convert from inches.