I attempted to model the spring/trigger mechanism that powers devices like the Autoject EI. They allow for the easy administration of medicine like insulin or epinephrine. This includes many pieces. *injector body - encases all components *plunger and firing button casing (blue in picture) - houses the springs and plunger rod, hold trigger button *plunger rod - pushes the syringe to inject medicine; powered by compression of 2 springs *spring holder (top and bottom)-balance the set of springs on the plunger rod *indicator (yellow in picture) - barrier between plunger rod and syringe base; aids in measurement of needle depth This turned out to be way beyond my CAD abilities, so hopefully someone can pick up where I left off and make this product available for those that cannot afford the commercial equivalent.