Engineering drawings are ubiquitously used for capturing, conveying and archiving innovative engineering designs. Many engineering companies' core intellectual property resides in their proprietary engineering drawings. Therefore, protection of such vital data is extremely important. This paper provides a swap-transformation matrix based approach to scramble engineering drawings in order to enable confidentiality. An engineering drawing involves the topological information and vertex information. The vertex information is more valuable than the topological information, since the vertices information primarily determines the content of engineering drawings. We argue that the vertex information is more valuable than the topological information, even if some topological information is lost, a drawing may be reconstructed from the vertex positions. We provide for three keys to ensure the security of the drawing. The technique can facilitate digital rights management of engineering drawings. The advantages of our technique are that scrambling is computationally less intensive than encryption and it allows for partial obfuscation.