BOX command
The BOX command is used to create 3d solid box.
Command Access:
Ribbon : 3D > Modeling > Box
Menu : Draw > Modeling > Box
Command : BOX
Command Prompts:
Specify first corner or [Center]: 
Specify other corner or [Cube/Length]:
Specify height or [2Point]:
Function Description:
The base of created cuboid is always parallel to XY plane of current UCS. Users could specify cuboids' height by inputting Z value; it could be positive or negative. Inputting a positive value, the box will be created along the positive direction of z axis; inputting a negative value, the box will be created along the negative direction. If the Z value of the other corner point is different from the first corner point, the command prompt of "specify height" will not display.

Relative Glossary:
Center : Create a cuboid by specified center.

Cube : Create a cuboid with equivalent length, width, and height.

Length: 
Create a cuboid by specified length, width, and height. The cuboid length is corresponding to X axis, the width is corresponding to Y axis, and the height is corresponding to Z axis.

Cube:
Create a cuboid with equivalent length, width, and height.

Length: 
Create a cuboid by specified length, width, and height. The cuboid length is corresponding to X axis, the width is corresponding to Y axis, and the height is corresponding to Z axis.

2point : Specify cuboid height by 2 points, the distance of 2 points determines cuboid height.
Related tutorial video:
- View command 00:25
 - Menus and Shortcut Menus 00:37
 - Unisolateobjects command 00:37
 - Qnew command 00:48
 - Status bar related setting 00:52
 - Box command 01:03
 - Union command 01:50
 - Xedges command 02:03
 - Filletedge command 02:08
 - Vscurrent command 02:45
 - Extrude command 03:27
 - Rectang command 04:22
 - Move command 04:45
 - Line command 05:06
 - ARC command 05:16
 - Trim command 05:23
 - Join command 05:46
 - Convtosurface command 06:35
 - Slice command 06:51
 - Solidedit 08:32
 
Above video sources from TUTORIAL - GETTING STARTED WITH GSTARCAD, enrol now for free.