Welcome to D.O. Smith, we are a product design and development workshop located in Los Angeles California. We have been in business since the first design and development of the first double test plug for plumbers which was made in 1939. Since then we have grown and expanded our services to include Computer numerical controlled product development (CNC), and have also built a factory to be able to create molds to work with metal materials which include Aluminium, Brass, and Cast-Iron. With both our CNC and foundry manufacturing we can design almost any product from the beginning stages to final product development.

CNC Machining

Full service Computer numerical control machining with experienced operator.

cnc operater
foundry work shop brass aluminium cadt iron

Metal Foundry

Aluminium, Brass, and Cast Iron metal casting work shop. 


Plumbers double test plugs.

plunbers test plugs

America Made

Quality product design and development.

d o dmith engineering