Trim table / screen mesh count question.

I was thinking about getting a new screen printing frame and building a trim table with it... what should i get for the mesh count of the screen?
The station would be a base with a glass top and a lip around the outside edge for the screen to sit in. I'll post a pic once I figure out the mesh count. I want to be able to collect a good amount of kief from all the trimming and thought that might work well...

I use a 120 micron but if you can make it use multiple

i was also thinking about using a couple screens, the top would be like 100, the middle would be like 120, and the bottom would be like 180-200, all stacked on glass.

I thought that 120 was a little to open
what are some common mesh counts for bubble bags?

220,190,120,73,40,25