Hi all,

I built a 4x5 pinhole camera that requires 0.56mm hole.
An empty coke can, 0.5mm dia needle and 800-1200 grade sandpapers were used to make the 'lens'.
However when I look closely with a high powered mag glass, the hole edges look rough like saw.
How can I make clean edged hole? Do you have any un-told tricks?
thanks