A block is a set of entities that are grouped together as a single entity. Blocks are used to create complex mechanisms as sketches and to check their functionality before being developed into complex three-dimensional (3D) models. The three blocks that have been created are displayed as Block-Crank, Block-Piston, and Block-Piston-tank. That the mating conditions were imposed on the blocks rather than on the assembly of parts. This is the advantage of using blocks because students can sketch in two dimensional (2D) and add relations to 2D sketches, which are synonymous with mates in assembly mode. When blocks are used, the Layout tool is used instead of the Assembly tool. Designing with blocks is similar to incontext editing that is used in the top–down approach, as students have already observed. Industrial and engineering designers often use blocks to experiment with various designs in 2D before committing resources to 3D design.