See my 6x12 link below (not pinhole though).
The limiting factor with pinholes is the ratio of pinhole diameter to material thickness. If you have a pinhole which is equal in diameter to the thickness of material, it will block any light from more than 45 degrees from perpendicular, limiting the field of view to 90 degrees. If you can use thinner material, there is less chance of vignetting. e.g. if the material thickness is one third of the hole's diameter, 143 degrees of coverage is theoretically possible.