Donald Holt, Founder (1934-2004) Assembling a Beltwinder for artificial kidney manufacturing, 1970.

Our History

Diamond Tool and Die was started in 1967 by its founder Donald Gene Holt. It began as a one-man job shop in Donald’s home garage. In 1968, Diamond Tool and Die incorporated and moved into its new home at 508 29th Avenue. At that time it was only 2,500 square foot wooden building.
In the early 1970s, Diamond Tool and Die helped design and manufacture artificial kidney dialysis machines and support equipment. Donald also designed and patented his revolutionary quick change tooling system known as Inmotion. Throughout the 70s and 80s Inmotion was manufactured and sold all over the world by Diamond Tool and Die.

In 1976, Diamond Tool & Die introduced a gas purifying product line known as LabClear™ and began a tooling distributing company known as The Tool Crib. In the early 1980s, DTD had built its first of six buildings and had grown to fifteen employees. In the late 80s DTD merged with another machine shop known as Apsco Manufacturing, started an ESOP (Employee Stock Ownership Plan), and introduced a moisture trap product line known as OxiClear™. In 1993 Donald Holt’s son, Darrell Holt, and Dan Welter became President and Vice President of the Corporation. The company soon became certified to manufacture nuclear fuel rod components and became a tailored ISO 9002 DoD (Department of Defense) contractor.

Diamond Tool and Die is where an owner makes every part.


Today, Diamond Tool and Die is housed in a 30,000 square foot facility.  There are over thirty-five employees/owners and they have over 75 machines on the floor (CNC/manual Mills & Lathes; EDMs, and CMMs). There is a full time Inspector and Chemical Engineer on site. DTD has in house Accounting, Programming, Job Costing, Quoting, Material Tracking, and Shipping and Receiving Departments. As a full service machine shop, DTD can assist with outside services in addition to our in-house machining of metals & plastics, finishing and inspection services. DTD runs day, night, and weekend shifts, so that they can assist with rush jobs and emergency services.

Our Employees

At Diamond Tool & Die, we realize that our employees are our most valuable resource. On average, our employees have been with us 26 years. Collectively, our employees have over 700 years in the manufacturing industry, giving DTD and its customers the benefit of their vast expertise and practical experience.


Diamond Tool & Die has a Safety Program with a Proven Record. All employees are responsible for complying with DTD’s Injury and Illness Prevention Program, safety rules and policies.

Community Involvement

For Diamond Tool & Die, being a successful business also means a responsibility to our community. DTD has a long history of contributing to the needs of many organizations and events in our Bay Area community, including the following:

  • Cub Scouts
  • Boy & Girl Scouts
  • Special Olympics
  • Alameda Elks Club
  • Meals on Wheels
  • Susan G. Komen For The Cure
  • Boys & Girls Clubs
  • Local Little League
  • Local Girls Softball
  • Local Boys & Girls High School Football, Baseball, Basketball & Volleyball
Cub Scouts learning how to machine