Credits for the label go to aonomus. I Just rearranged the contents to fit the 89x42mm labels which I use (Software: Dymo LabelWriter to open the .label file).
This is a "working" auto-injector. This is NOT A TOY!
I am not responsible for ANY injuries caused by building and operating this design!
added photo or the "real-world" assembly
1x 3ml syringe (concentric needle)
1x polystyrol centrifuge tube 100 x 16mm ("Böttger Zentrifugenröhrchen")
1x needle of your choice, i prefer 1mm needles
1x steel spring OD 11mm, length 60mm, compressed length max 20mm
Cut the syringe housing at the 2.5 ml mark - syringe housing should now be 45mm in length (from the tip to the cut).
Cut the syringe plunger to 40mm length.
First assemble the syringe with the needle guide.
Then load the spring between the syringe base and endcap - plug in the safety cap to not fire the thing by accident ;)
Then plug the syringe shaft into the spring assembly.
Now load 1ml fluid to the syringe and finally plug the whole assembly into the tube. - > DONE and ready to "unload" into something....
Cut the needle to your preferred length (should definitive be inside the tube on loaded spring).
Assembly is designed to hold 1ml of fluid in syringe.
Extremely pimped RRP Mendel
dont print too fast, accuracy is required.
syringe spring base:
carefully flatten the lower 45° face to get better hold of the loaded spring when removing the safety cap.
carefully adjust the hole (widen) until it fits and sticks on the needle base.
Test your assembly, my centrifuge tube was conical so a little reduction of the two hex guide's diameter is required. You can achieve that by sanding the 6 edges a little.
The final assembly should be able to push the syringe to the tube bottom and push the syringe shaft all the way down.