Funny you should mention it, as I type without using the index finger on my left hand. 30 stitches...and I have no idea what I did wrong. In my case it was  a Super Tigre 90, inverse mount, on a World FunWorld 3D and a 13x6 APC prop. I finished tuning the needle from behind the plane on the right side. My radio (I fly with an over shoulder aluminum tray) was on the starting stand in front of me. I finished my tuning, picked up the radio by the shoulder strut of the tray, and started to walk out to the front of the plane to go around to the left side to pick it up. To do this I put the tray on the position it will be in when I fly and pick the plane up in both hands-weight supported on my right with the lef t holding it by the wing.I never got to this point.  Somehow as I walked to the front of the plane  (still on the right side of it) I managed to get the thumb side of my left index finger. Obviously I "cut the corner" somehow. Lessons? I wish every manufacturer took a page from OS and use a remote mount needle (even though that had nothing to do with this particular injury), inverted motors add a level of awkwardness in access (again, not a direct factor here, but...), removing any glow driver from an inverted motor tail dragger adds yet more awkwardness(another non-factor as an issue in this case), and grey props (APC) are much less visible than contrasty black ones (MA), particularly when the manufacturer has painted the tips white. My safety officer and I are now corresponding about the starting stand design and starting procedures, and my next APC prop will get a paint bath of some super-contrasty color on the blade tips. I still wish I could figure out more about how the accident happened, though. Maybe I was more preoccupied with those other supposed non-issue factors than I thought and that distracted me? Or maybe my color deficient eyes just did not see the prop.