FA info icon.svg Angle down icon.svg Project data
Authors Natalie J. McGrath
Completed 2019
Made No
Replicated No
Cost USD 6
Instance of Spring-loaded syringe
OKH Manifest Download

AutoInjectors are a spring-loaded device that aides in delivering the proper dosages of certain medicines. The have built-in adjusters to ensure the medicine is delivered at the proper depth in the body. They are useful for those that have trouble using a simple needle for injections, possibly children, the elderly, or those with needle-phobias. They are also useful for injecting pets with their medication. The AutoInjector keeps the needle covered until injection time to prevent injury, and some have a built-in safe measure of requiring the injector to be pushed against the skin before the trigger button can be pushed to prevent accidental discharge.

Bill of Materials[edit | edit source]

  1. 3.5" by.5" Spring
  2. 3" by.25" Spring
  3. 1.5" by.5" Spring
  • Optional Clear Plane to use as Window; leaving open works fine as well
  • Glue, like a hot glue gun
  • all colors are notional and used to specify which piece is being referred to
Disassembled AutoInjector
  1. Glue Spring holder Top and Bottom pieces together
  2. Use hot glue to create small cushion on end of plunger rod, if desired, for comfort and to aid in stabilizing rod
  3. Place the 1st spring onto the plunger rod.
  4. Insert the spring holder with the smaller top into the spring with the plunger rod through the middle
  5. Place the 3rd spring onto the plunger rod, so that it falls into the spring holder.
  6. Place "yellow" indicator piece onto groves inside "blue" plunger and trigger button piece, with indicator marks facing the viewing hole in the "blue" piece
  7. Place small end of plunger rod through small hole at the top of the "blue" plunger and trigger button piece
  8. Place wide end of plunger rod into "yellow" indicator piece. You will have to compress the springs to do this
  9. Insert #2 spring followed by assembled pieces into Injector body. You will have to push down the trigger button in order to slide the pieces into the body
  10. Thread long depth adapter into syringe housing
  11. Insert primer/depth guide into long depth adapter
  12. Use syringe housing unit to set springs by inserting it into injector body, as far as it will go
  13. Remove from injector body once springs are set
  14. Twist syringe housing unit on assemble pieces

Tools needed[edit | edit source]

Technical Specifications and Assembly Instructions[edit | edit source]

The Injector Body needs supports generated when printed for the Trigger Button window; these will be snapped off after printing.

About 4 hours to print all of the parts.

5-10 min for final assembly.

Common Problems and Solutions[edit | edit source]

  • Make sure the springs are loaded properly. Spring positions are not interchangeable*

This project was way beyond my CAD abilities, so not all of the pieces are optimized for printing; Hopefully a someone can improve upon my design

Cost savings[edit | edit source]

  • $1 for plastic, $5 for springs, $6 in total
  • $27.99 Owen Mumford Autoject EI [1]
  • $22 total savings or a 78% price reduction.

Benefited Internet Communities[edit | edit source]

References[edit | edit source]

  • DallasMTBR, director. About the Autoject 2. Youtube - About the Autoject 2, Youtube, 18 June 2017.
  • Owen Mumford. Autoject-Brochure. Autoject-Brochure
  • Rawlings, Kelly. "Injection Helpers.", 2015,

External links[edit | edit source]

FA info icon.svg Angle down icon.svg Page data
Keywords 3d printing, autoinjector, medicine delivery, osat, plastic, springs
SDG SDG03 Good health and well-being
Authors Natalie J. McGrath
License CC-BY-SA-3.0
Organizations MTU, Michigan_Tech's_Open_Sustainability_Technology_Lab, MY4777
Language English (en)
Translations Spanish, Chinese
Related 2 subpages, 5 pages link here
Impact 777 page views
Created December 5, 2019 by Natalie J. McGrath
Modified May 16, 2024 by StandardWikitext bot
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