If you've been following the Digital Pinhole stuff, here is part 2 in the series on how to make a body cap pinhole lens.
Alternatively you could use the sharpie marker to paint the whole disk and masking in that case would not be required. However painting with a flat paint works better.
Do this in small incremental steps so you don't oversize the hole. Once the hole is too large there is no way to make it smaller.
However making a new aluminum disk is easy. Just replace the disk with a new one following steps 4-14.
In the next post we'll test out the lens and see how well we did.