[snip]
- Shelves will be held in-place by a pair of 1/4" shelf pins at each
end. I plan to use sleeves to reinforce the shelf-pin holes.

[snip]

Are the shelved attached to the case? If not, you could finish both sides
and flip the shelves occasionally. What bends one way will bend the other -
that sort of thing. I do this with closet top shelves of 1" pine that sag
over time. When flipped they straighten out and eventually sag the other
way.

Josie