Tub Ventilation

[chosen2030]

So I recently found tubs (roughly 16 qt) that just about perfectly fit into an old bookshelf that I have:

As you can see, it is enclosed on the sides but open front and back. I was planning to use a soldering iron to make ventilation holes into the tub, so I was wondering: 1) placement of the holes (front & back, sides, top or all around)?; and 2) number of holes (about the size of a pencil eraser)?

I know that ventilation is important to control the humidity, so please keep in mind: 1) the tubs will have lids on them, and 2) that I live in Arizona where the annual average for daily humidity is only 35%...it's a dry heat

 

[Neon Aurora]

I currently use a lid on my hatchling tub because I don't have shelves that fit it. I found that they retain wayyy too much moisture with just holes in the top. I cut out the inside part of the lid (leaving the part that latches on) and replaced it with cheap screen using a bit of duct tape. It works very well for me.
I also used a soldering iron to make some holes around the sides. I didn't make them very big because feeders can sometimes get out of them