APL (Dyalog Unicode), 74 49 bytesSBCS
{(⌽∘⍉⍵@(2/¨⍳x))⍣4(⍉(⍵,1↓⌽⍵)@x)⍣2⊢''⍴⍨2⍴1-⍨2×x←≢⍵}
-6 thanks to ovs
APL (Dyalog Unicode),
Ven
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