In this instructable, I am going to show how to model the above mug using SelfCAD software.
SelfCAD is a browser-based 3D software that allows one to model, sculpt and print models all under one program. Visit www.selfcad.com to start your one month free trial and later pay $4.99/m or $39.99/yr but if you are a student or teacher, SelfCAD is free for you, click this link to register SelfCAD for Students.
Once you have registered click Launch the Editor and everything will be set

The tools that we are going to use are, Sculpting, Magic Fix and Boolean Difference.

Step 1: Start Modeling

In the Basic Shapes section select the cylinder.
In the Transformations section, Select the Scale tool and increase the height to 150, and using the Taper tool scale the cylinder as shown in the second image above. The Base of the cylinder is now ready.
Select the Sculpting tool found in the Tools section. In the sculpting, we can change the model using the brushes and the settings given.
Turn OFF the Symmetry and using the Standard Brush draw a line as shown in the third image above.
Now Turn ON the Symmetry and adjust the size of the brushes to 114.
When you select the + it will draw on top of the model and vise versa.
Using the Masking Brush, select the some parts of the top segement. The parts selected by this brush won't be affected by the other brushes.
Using the Standard brush select the area just beneath the area selected by the Masking Brush. Using the Move Brush, move the the selected areas.
Select the Smooth Brush (Can do this by pressing and holding Shift) and smooth the model.
Select the Remesh tool found on the top right hand-side. This breaks the Geometry and converts them into a set of quads and this helps to get a better quality of the model.

Step 2: Drawing the Cup

Using the Sculpting, Magic Fix and Boolean Difference adjust the model to be like the shape of a cup. Check the video above to see how to achieve this.
When drawing using the brushes you will realise that the model looks worse than actual it should be, but when you use Smooth Brush and magic Fix and this makes the model smooth and look real.
After drawing, click Sculpting and our model will look like the 3rd image above.
After Sculpting the shape is very heavy and has a complex structure. To simplify the model the Resolution tool is the one that will be used. Set the resolution to 0 and click Rebuild and our shape will be simpler now as shown in the 4th image above.
Select the Magic Fix tool found in the Tools section. This changes the Structure and smooth ens the object.
Turn on Keep the Original object in order to compire the top shapes and click apply. Check the 5th Image above to see how it will look like.
The Shapes look similar, but the difference is, the bottom shape is rebuild with less polygons but the other one looks smoother.

While using the top shape, add another cylinder. Select Scale Tool and set the X, Y and Z settings to 84, 150 and 84 respectively.
Using the Taper tool scale it down to be as shown in the 1st image above and position it to 0,0,0.
Focus the Camera on Top and align the new shape.
Select the two models and select Boolean, select Difference and in the Select the Object to Extract tab click the first option, in my case it's Obj_3 and then click Apply.
To simply the object Structure for 3D printing select Magic Fix and click Apply.