When producing your cover letter, emphasize your ability to create original designs as well as modify existing ones, and not only bring these designs to fruition, but to success for the company. List out the breadth of projects you have been involved with, and discuss the various contractors, labs, consultants and production teams you have worked with to get the job done. Highlight your knowledge of codes, regulations or standards that had to be worked into your projects. Talk about the size and number of contract negotiations you have been involved with, and your ability to accurately source, cost and produce quotes for required materials. Discuss any research and studies you performed for your designs, and any quality controls you implemented for a successful final product. Be sure to emphasize a design that was innovative or cutting edge as well as profitable and well-received. You may consider telling an anecdote about a particularly difficult design problem with an existing product, and how your redesign turned the profitability of the product around.
Your cover letter should present you as an individual who can not only get the work done, but can also be a part of a team that presents and sells projects to board members, upper management or clients. Talk about any demonstrations of your design you have given, and how you were able to gain support for your design through an effective presentation. List any internal employee or client training you have done of your products.