I like the idea behind the mask but I really see two problems that, for me, would be a problem over the B. mask I made by hand:

1) If doing a mask by hand it is going to be really tough to keep the lines straight...and because that 2 degree difference is kinda small, my exacto knife cutting error may be greater than that two degrees. I know my B. Mask isnt perfect when I cut it, bt works really well and gets me as close enough (with the equipment I have).

2) Even with a perfect mask, I think I would have trouble seeing the two spikes on my canon 300d LCD. The resolution isnt that great on the LCD and even at highest zoom, I think I would have problems. I would have to d/l each pic and check with an image viewer to probably see things, and with the transfer rate from my 300d it would be horribly slow.

For others with better rear LCDs, and/or quicker downloads from their cameras it may be easier to see...and work better...but for my camera and laptop, I dont think it would work as well as a B. Mask