Custom Plastics Injection Molding

Solving problems with injection molded plastic solutions.

Family owned and operated since 1973.

(909) 984-0200

Ontario, CA


(574) 259-2340

Mishawaka, IN


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Your #1 leader for spin weld FittingsYour #1 leader for Spin Weld Fittings

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Your #1 leader for Spin Weld Fittings

100% made in the USA

CUSTOM PLASTICS provides a range of products, all made through the injection molding process.  We have been providing plastic solutions for over 45 years.


We provide:

  • A large range of products for the Roto Molding Industry
  • Raised and Flush Threaded Fittings
  • Bosses
  • Patches
  • Sensors and Blind Inserts
  • Grommets
  • Bulkhead Fittings


  • Numerous sizes of caps, plugs, and lids
  • Other injected molded proprietary products
  • Lick Wheels
  • Vents (vacuum and pressure relief)
  • Holding Tank Adapters
  • Roof Vent Caps

  • Custom Molding
  • Reverse Threads
  • Double Ended Threads
  • Vortex Attachments
  • Special Colors


CUSTOM PLASTICS has established itself as being responsive to all special requirements that will aid its customers in gaining an advantage in competitive pricing.


  • We try to maintain a balance between proprietary items and custom items. This is a healthy situation for growth.
  • We have in house tool design that minimizes lead time.
  • We maintain our own machine shop for mold and tool repair and use five local tool shops for new tooling. We are located in a very competitive market for new tooling for our custom and proprietary products.
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1305 West Brooks Street

Ontario, California 91762


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(909) 984-0200

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