I love the enthusiasm but this is dangerous.

Hi all, I am a Mechanical Engineer by day and design Medical devices such as auto injectors at work. I really appreciate the fact that you guys are willing to donate your time to the cause of creating an open pen to help those who cant afford the ridiculous price of the epipen. I don't doubt that you guys are capable of creating a pen that functions correctly. I fear however for the person that prints a pen that doesn't fire properly in a time of need. I deal with FDA compliance and the rigors of an engineering QMS that has the necessary documentation to bring something such as a medical device to market and they seriously dont fuck around. The entire process is basically documenting who the scape goat is if different things go wrong. Ultimately its the CEO or manufacturer that is responsible. This open pen idea would make the FDA very uncomfortable because it becomes unclear who is responsible if something goes wrong. This typically causes the FDA to very aggressively stop the thing that makes them uncomfortable, unmercifully, any way they can. That's included and not limited to jail time and fines.

For the design I think everyone is in agreement that a pre-filled syringe is the way to go. They are cheap, and easy to replace. Instead of designing a 3d printed pen that could potentially misfire and kill someone, I would suggest using something already cleared by the FDA to do this exact function such as a syringe auto-injector. They exist for diabetics injecting insulin and accept standard syringe sizes. They are affordable, reusable, and also wont accidentally kill someone. An example of one can be seen here https://www.amazon.com/AUTOJECT-SELF-MUMFORD-Choice-One/dp/B004N10F7U but three are many more on the market probably for cheaper. If any of yall have more specific questions hit me up, but I think your just asking for trouble trying to solve this problem with 3d printing. Especially when such a cheap "legitimate" option is available. If you are really concerned about the price of an epipen spread the knowledge that there is a cheap, ready made alternative. Don't reinvent the wheel and potentially hurt someone.