You can download a free software to design your camera with existing lego parts. When the design is over , you can buy whatever and how many parts ever used in your design. This is fully automatic order system within their website.
Only pinhole camera I can invest time is the pinhole anamorphic camera. Your second camera could be that. I liked the box very much and the pinhole with a shutter and release cord.
May be you could glue every part to protect it from impacts.
I reallly loved this lego camera. Congrulations.