gistfile1.txt

∇ wrapBox (v) {
  w ← (⍴v)[1]
  {((⊂"┏") , (w ⍴ ⊂"━") , ⊂"┓"),[0]⍵,[0](⊂"┗") , (w ⍴ ⊂"━") , ⊂"┛"} (⊂"┃") , v , ⊂"┃"
}

∇ render2d (v) {
  w ← ((⍴v) ⍴ ⌈/[0] {(⍴⍵)[1]}¨v) {((↑⍴⍵) (⍺-(⍴⍵)[1]) ⍴ (⊂" ")),⍵}¨ v
  wrapBox ⊃ ,[0]/ {⍺,(⊂" "),⍵}/ (⍉ (⍴w) ⍴ ⌈/[1] {↑⍴⍵}¨w) {⍵ ,[0] ((⍺-↑⍴⍵) ((⍴⍵)[1])) ⍴ (⊂" ")}¨w
}

Commented version:

∇ wrapBoxX (strlist) {
  w ← (⍴ strlist)[1]
  top ← (⊂"┏") , (w ⍴ ⊂"━") , ⊂"┓"
  bottom ← (⊂"┗") , (w ⍴ ⊂"━") , ⊂"┛"
  {top,[0]⍵,[0]bottom} (⊂"┃") , strlist , ⊂"┃"
}

∇ render2d (v) {
  v ← v

  ⍝ The width of each column is the maximum width of any cell
  colWidths ← ⌈/[0] {(⍴⍵)[1]}¨v
  ⍝ Pad each cell to the correct width
  xAligned ← ((⍴v) ⍴ colWidths) {((↑⍴⍵) (⍺-(⍴⍵)[1]) ⍴ (⊂" ")),⍵}¨ v

  ⍝ Compute the height of each row in a similar way as the cols
  colHeights ← ⌈/[1] {↑⍴⍵}¨xAligned
  ⍝ Pad each row so that they are all the same height
  yAligned ← (⍉ (⍴ xAligned) ⍴ colHeights) {⍵ ,[0] ((⍺-↑⍴⍵) ((⍴⍵)[1])) ⍴ (⊂" ")}¨ xAligned

  ⍝ Add a space between cells on each row
  vSeparated ← {⍺,(⊂" "),⍵}/ yAligned

  wrapBox ⊃ ,[0]/ vSeparated
}