Jelly, 119 118 bytes

WHAM

“ƭH[Ȥ9);¦8¬ụḷPç£Ɗz"\ʂʠRØ)ṖṾĠ€|ḌḄ'"rƈ!ṇṭ~Wẋj’ṃ“|\ _”s7;€“| |”µṚ“\/”y;µ€U5R¤¦s6Ṛ
“Þ}ỌGṗo’ṃ“ -|.'”s4µṪẋ7ṭµ€m€0s3jЀ¢Ṛ€Y€Y

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How?

“...’ṃ“|\ _”s7;€“| |”µṚ“\/”y;µ€U5R¤¦s6Ṛ - Link 1: middle rows of blocks: no arguments
“...’                                   - base 250 number
     ṃ“|\ _”                            - convert to base 4 with digits [0-3]="_|\ "
            s7                          - split into sevens
                “| |”                   - literal "| |"
              ;€                        - concatenate €ach
                     µ                  - monadic chain separation (call that rhs)
                             µ€         - for each r in rhs:
                      Ṛ                 -     reverse r
                       “\/”y            -     convert any '\'s to '/'s
                            ;           -     concatenate with r
                                   ¦    - apply to indexes...
                                  ¤     -   nilad followed by link(s) as a nilad
                                5R      -     range(5) = [1,2,3,4,5]
                               U        -   upend
                                    s6  - split into sixes
                                      Ṛ - reverse

“Þ}ỌGṗo’ṃ“ -|.'”s4µṪẋ7ṭµ€m€0s3jЀ¢Ṛ€Y€Y - Main link: no arguments
“Þ}ỌGṗo’                                - base 250 number
        ṃ“ -|.'”                        - convert to base 5 with digits [0-4]="' -|."
                s4                      - split into fours
                  µ                     - monadic chain separation (call that lhs)
                       µ€               - for each l in lhs:
                   Ṫ                    -   tail l
                    ẋ7                  -   repeat (the tail) seven times
                      ṭ                 -   tack to l
                         m€0            - reflect €ach
                            s3          - split into threes
                                 ¢      - call last link (1) as a nilad
                              jЀ       - join mapped over right
                                  Ṛ€    - reverse €ach
                                    Y€  - join each with newlines
                                      Y - join with newlines
                                        - implicit print