This is cool! Up and coming pinhole camera manufacturer 8 Banners has come out with their latest offering, a multi pinhole turret with built in shutter.

This turret can be mounted as an accessory on the various models of pinhole camera made by 8banners with the exception of Ma.
It replaces the normal shutter assembly by having instead of the choice of 1 pinhole plates but 6 pinhole plates.
For the 4×5 model, if u dun put in a plate for one of the hole, it can become a view finder that cast an image in the ground glass back behind the cam.

The idea of using an empty space as a viewfinder is beautiful. The greatest thing about 8 Banners, other than the cameras, is that they are very DIY friendly. You can but pinholes viewfinders, and shutters there at quite reasonable prices. The turret is lists as being $85US. Quite affordable if you ask me.
See more:
Turret Set on Flickr - Photo Sharing!