2 Saved 3 bytes by not trying to be clever.

Pyth, 4340 bytes

Ks[d\K" /d\\d)" \ ""  ^"Kj+b+*2+d\\b*Q]*3"| "_K"  v


Fairly similar to Steven Hewitt's, but developed independently.

Explanation

Ks[d\K" /d\\d)" \ ""  ^"Kj+b+*2+d\\b*Q]*3"| "_K"  v
Ks[d\K" /d\\d) \ ""                                 Set K = " / \ "
"  ^"                       "  v  Draw the end points.
K                    _K      Draw the slants.
*Q]*3"| "        Draw the vertical bars...
j+b+*2+d\\b                 ... interspersed with slants.


Pyth, 43 bytes

Ks[d\/d\\d)"  ^"Kj+b+*2+d\\b*Q]*3"| "_K"  v


Fairly similar to Steven Hewitt's, but developed independently.

Try it Online

Explanation

Ks[d\/d\\d)"  ^"Kj+b+*2+d\\b*Q]*3"| "_K"  v
Ks[d\/d\\d)                                  Set K = " / \ "
"  ^"                       "  v  Draw the end points.
K                    _K      Draw the slants.
*Q]*3"| "        Draw the vertical bars...
j+b+*2+d\\b                 ... interspersed with slants.


Pyth, 40 bytes

K" / \ ""  ^"Kj+b+*2+d\\b*Q]*3"| "_K"  v


Fairly similar to Steven Hewitt's, but developed independently.

Try it Online

Explanation

K" / \ ""  ^"Kj+b+*2+d\\b*Q]*3"| "_K"  v
K" / \ ""                                 Set K = " / \ "
"  ^"                       "  v  Draw the end points.
K                    _K      Draw the slants.
*Q]*3"| "        Draw the vertical bars...
j+b+*2+d\\b                 ... interspersed with slants.

1

Pyth, 43 bytes

Ks[d\/d\\d)"  ^"Kj+b+*2+d\\b*Q]*3"| "_K"  v


Fairly similar to Steven Hewitt's, but developed independently.

Try it Online

Explanation

Ks[d\/d\\d)"  ^"Kj+b+*2+d\\b*Q]*3"| "_K"  v
Ks[d\/d\\d)                                  Set K = " / \ "
"  ^"                       "  v  Draw the end points.
K                    _K      Draw the slants.
*Q]*3"| "        Draw the vertical bars...
j+b+*2+d\\b                 ... interspersed with slants.