My piece of metal comes from a watch.Pretty thin but I can do better.I am still looking to find this type of parts of metal with tiny perfect holes.I am knew in photography, of course in pinhole too.Thank you for your advices, I will try to go over all of them.Maybe I can make my images sharper.
I use b&w 5mm ISO100 and colour film for ISO200.I got to feel what exposure I should use.About the composition, well it's harder.I just guess where the camera points at.And I think my angle of view is ~44.6degrees.
I just bought a Zenit E from an antiques sale, street market.Works perfect.I try to use it to see what the angle looks like in my viewfinder.I point and shoot and in my mind I have that composition for my sight, my 37 degrees angle.Sometimes you have to guess.
I went to many sites but still it is too hard to real use that info about your pinhole with your own, it is too hard to measure it or make it a perfect circle.That bugs me.BUT, what I love about this thing is that I will try to improve mine until I get it right!I am too close to having a perfect pinhole camera .And of course, I love what I am doing.

Less is pinhole!