Blocking Panel

• Blocksize: define the block size (in Blender units or meters) you want to work with. The default size 1 is pretty nice to work with, but you can adjust it. 
• Add Cube Primitive: Adds a cube into the scene, right on top of the world origin. 
• The X, Y and Z buttons: Makes a copy of the cube in one of the axis. For example, +Z is up, -Z is down. 
• Join: Select all the generated cubes and press join. This will remove the doubles and the interior faces. 
• Origin to 3D cursor: Places the origin or the generated object at the same position as the world's origin. 
• Alt+K: Select one of the cube primitives, and press Alt+K while hovering the mouse over one of the faces. This does makes a copy on the hovered face.

Geonodes Panel

After placing some cubes and joining them, you can select one of the modifiers. Start with low-poly and I suggest to get familiar with the behavior of the modifiers. A more extensive documentation will follow later.  

Styles Panel 

This is from an older version of the Blocker addon but still useful. It is using Blender's existing modifiers. I suggest not to use two styles after each other because you might end up with a very high poly count. 

• BevelSurf: Adds a simple bevel modifier and then a subsurf. 
• 3xSubsurf: A subsurf modifier with 3 levels. 
• Truss: Transforms your mesh into a truss
• Shape Gen: Very Useful! Play with the modifier stack and you see all kinds of variations of your mesh.  Adjust the factor of the cast modifier and the scale of the Remesh modifier. 
• Low Poly: Makes a low poly style of your mesh
• Apply Modifiers: Applies the modifiers. 

Mods Panel 

Mods are safe to combine, which was not the case with styling. 

• Add Mirror modifier: Adds a mirror modifier to make mesh symmetrical.  Switch axis on/off in the modifier stack
• Add Taper: Taper modifier is already on Z-axis, so that saves some time.  You only need to adjust the factor.