I'm also interested in knowing more about 3D printing. I need some precision (+/- .002" or so) parts made in a no larger that 2" dimension, My experience of the 3D printed stuff has been not too close tolerance and kind of rubbery material. The reports above suggest much better is possible. Ideally they would be machined from Delrin but that would cost me as much as a 3D printer. These would be adapters for microphones for acoustic calibration like the one below.
I don't know if +/- .002" is achievable or not. It would take some time to calibrate and tune your printer. Even then, you would probably need to print several prints and adjust the scaling. The scaling changes a little with filament types. From the work I've done on my printer trying to match exact sizes, it would be worth a try.
Is Delrin a soft material? What are you looking for?
PLA is a hard plastic after printing and tends to crack instead of flexing. There are a range of material you can print from very soft like those rubber iPhone cases to carbon fiber material.
Check this video showing the process to get desired dimensions:
Edit:
Just took some measurements of the scope feet I made not long ago. Printed in PLA.
Designed to 0.8" x 0.2" and they came out at 0.808" width x 0.19" height without really trying.
So, it appears to me that you could probably meet your tolerances.