pinhole resource will be able to sell you a laser cut pinhole,
there is also someone named pinholebilly, or something like that
(i wish i could remember what it was .. )
the image circle covers 3"x the focal length or so ..

i am sure enlarging filters would work well to deal with contrast
but with a (big) lens it might be hard to find a filter big enough to cover the whole
lens ... unless of course it is a pinhole then it is easy

if you want to have a little bit of fun ...
stick some paper in your 35mm camera and
process it to see how the contrast thing is
use different developers, different dilutions,
ages &C to see how it will effect your negative ...

have fun!

john