Most boxes I've seen have a very small micron metal screen, likely aluminum or stainless steel. It's not that hard to make one. It's basically some small pieces of wood, you need small nails, and you need need to predrill the holes for the nails to hold the screen. Then use wood glue to attach the two pieces to hold the screen. Most I've seen are held together by wood glue & small nails. Then a mirror in the bottom, or just glass, sometimes a small metal box.
It's a high precision task. If you're not a woodworker, just buy one.
Yea, dried & cure is better.
You can also get a kief grinder, it's not the best, but it's damn close. You can make hash balls from it(though it'd take a lot).