Here are OpenSCAD scripts to create customized fingers for prosthetic hands. There is one file to create the proximal phalanges, one file to create a combined distal/intermediate phalanges, and an additional file to create extra pins (to go along with one of the possible, selectable options).
Each file includes a great number of possible customizations that can be selected or modified in the Parameters section of the files. For example, you can set a scale factor, a finger tab width, a finger joint length, standard knuckle size, variations from standard size, string size, bungee size, knuckle hole size, whether to use a pin in the proximal-intermediate joint, whether to use a tie-off or a standard hole for the bungee, whether to use minkowski to smooth the print or just skip it and do a quick render, and whether to include support on some parts to make for cleaner prints.
I have simplified the parts quite a bit from the initial version, so that they now render much faster. I have tried to include every useful option I can think of. If there is some option you wish was there, but that is not, let me know - maybe I will add it.
I have included a full set of sample .stl files the way that I like them for the hand I am currently making. Those are more examples than anything else. I am a big believer in taking the time to customize each finger to your own needs.
Open the .scad files in OpenSCAD. Modify the parameters to suit your needs. Compile and render (f6). Then export the results as an .stl file. I recommend running the resultant .stl through Netfabb or some similar. That said, I have gone to great extents to try to ensure that the .stl files these scripts produce are clean. I have printed a full set of fingers without any .stl errors on any of the parts. I will usually leave the Use_Mink parameter at false until I see that I have the other settings the way I want. I then set Use_Mink to true and do the final compile/render. The reason is that the render with minkowski can take as much as a couple hours (though it is generally faster in this version than it was in the previous one).
I am printing these out of PLA. They should basically work the same out of ABS. The one part that might not work the same is if you select to use pins. I am using a modified version of whpthomas's nice PLA pin library v2 (thing 130879). He made that part specifically because the existing ABS version did not work well for PLA. There is a good chance that the PLA version will not work for ABS. If that proves to be a problem, I can probably add another parameter to select PLA or ABS.
I have gone, in OpenSCAD, to Edit-->Preferences-->Advanced and increased the element limit to 8000. If you have a lower value, you might see some pretty wonky results when you try to compile the script.