This is a basic cup/mug with a rounded gamdle that I made while learning the basics of FreeCAD 0.20. The current photo is scaled at 100%, The included Ender 3 sliced files are for 125% and 150% scaling. 125% is on par with normal mugs; however I tend to go for much larger mug for the morning coffee.

The model seems to work well in normal quality for the Ender 3 pro. with a .3 layer height @ 100 mm/s print speed. Supports are needed for the handle. Both infil and supports are best at 10%. 

Post processing: 

Although the model will hold hot or cold liquids after printing; I recommend a light sanding and then a food-grade spray finish.