@MagicOctopusUrn Well, we can create a square-box with a single dimension and single character using 25'A4206Λ (where 4206 means down→right→up→let, and which can be golfed to ŽG~). But unfortunately not with two dimensions, or with a different corner character. And since .Λ is bugged right now, not returning a string to modify further (it currently acts exactly the same as Λ), we also can't remove rows/column to fix the width/height, nor change the corners manually.
