I've been experimenting with producing course grained pictures. I have done it using HP5+ and TMZ, both 35mm. Obviously, the TMZ grain is larger than the HP5+. I have been doing this only in the studio where I have control over the lighting. My technique has settled on reducing the lighting ratio, over-exposing the film by at least 2-3 stops, and then under developing in Rodinal. I then print the resulting negatives using a very high contrast filter. The high contrast filter really exaggerates the grainy look.
I am very pleased with the results and now have two of the HP5+ pictures hanging in my office at work (see attachment). I can get TMZ sized grain from HP5+ by doubling the enlargement size and cropping down (as in these examples), but you have to plan for that when you're shooting.
I plan to be doing a lot more of this is the future. And that's coming from someone who has, up to now, made it his mission in life to squeeze the best fine grain performance possible out of a 35mm frame. I also plan to try print developer sometime, since it's often highly recommended.
-Dave