This is based off of the fantastic CAD model by Ivan Spasic https://grabcad.com/library/flintlock-mechanism-3-positions. I divided the model into parts and converted them into stl files for printing. All the parts can be downloaded at once in the "flintlock" zip file.

The cock, lock plate, and frizzen each have two versions. A whole part and a "split" part that I split in half to make it easier to print. Glue the halves together. The tumbler is the only part that needs supports.

The springs (in red) were printed in PET to be flexible. The rest was printed in PLA.