Custom circuits can very beneficial for many projects.

With some knowledge of electrical properties and component operation, a circuit can be designed using software that allows the actual traces or pathways for flow of electrons. The software used by the CSP is called Circuit Maker 2000.

Once the file is made, several Gerber files + a drill file must be exported so they can be sent to a company that will manufacture the printed circuit board.

Electric circuit projects
Making Printed Circuit Boards

Using Circuit Maker 2000 to output Gerber + drill files
Stencils for SMT printed circuit boards -- http://www.gplotting.com/