I tried several different materials in trying to mold my ring finger, the first of which was 300Q in alginate. The resolution of the result was passable, but there were several defects and no knuckle on the finger. On the plus side, the finger was very strong. Doing a better job of measuring equal parts of the 300 Q might help make a better mold.

300Q in alginate:

 

Next I tried plaster in alginate (not showed here). The result was very high quality, but upon taking the plaster out of the alginate my finger broke and I had to scrap it.

After seeing the success Ethan had with the 300 Q (I think it was 300 Q) I decided to try it again, but be exceptionally careful in measuring out equal quantities of the chemicals. To prevent wasting material I inserted two thin acrylic sheets so that only my ring finger would be cast.

 

The result was pretty horrid. I actually immediately threw the finger away, but pulled it out of the trash to take this picture and show how bad it really was.

 

Finally I went back to plaster, which seems to be the cheapest and best (but slowest) way to make high resolution casts. I cast all of my fingers up to the knuckles, taking care to isolate my ring finger.

 

After some cutting, chiseling, and sanding with a very high grit sandpaper my finger is complete: