I have wanted to do this for awhile now, and finally got around to it and I am glad I did, I took my microscope today and examined the 0.09mm slit (one of 4 that comes with the Plab kit you can order, for various slit widths,) as I had suspected there are many imperfections riddled throughout the slit entrance area.

I'm not sure if these imperfections really pose any real attenuation of signal exiting the slit or distortion effects, but I am going to try an open air slit design of the same size and see if there is any difference.

Any comments or questions are welcomed.

http://publiclab.org/notes/dhaffnersr/08-19-2016/microscopic-view-of-public-lab-s-acetate-film-slits