They have published instructions for the "EpiPencil", an epinephrine autoinjector, and the "Apothecary MicroLab", a do-it-yourself (DIY) device intended to make a variety of medications, most notably pyrimethamine (Daraprim).

[2] His motivation in founding the group is to provide medication to people when it is too expensive for them to afford, illegal to acquire, or unavailable due to it treating an orphan disease.

He believes that providing lifesaving medication to those who need it justifies violating the intellectual property rights of pharmaceutical companies, and supports cognitive liberty.

[4] Four Thieves had formerly partnered with Chematica to develop recipes for the group's medication,[2] but this ended and they lost access to information and software they had been given after pharmaceutical company Merck bought the startup.

[1] In 2016, after the price for an EpiPen was raised from $57 to $318 by its manufacturer Mylan, Four Thieves released instructions for how to build an "EpiPencil", a homemade epinephrine autoinjector that can be built for $30.

[10] Jose Gomez-Marquez, who is researching pharmaceuticals at MIT, has stated his belief that the group is more about publicity than medication, and is concerned about the danger of unvetted information being published.