I'd say the use of $' is less than obvious. Nice work btw.

The shortest solution I know (not my own creation):

for$;(0..2){say map{substr'   | |_|_ _ _|',vec('0123456789abcdef',$;.$
+_,4),3}"@_"=~/./g}
[download]

where '0123456789abcdef' is to be substituted with "\x09\x99\x90\x99\x99\x13\xBB\x75\x17\x55\x15\xB7\xB1\x15\xB5". When the \x codes are replaced with the actual characters, it comes out two characters shorter than the solution above. (Not very elegant, though.)

Cool!

Could be shortened by two chars using the same tricks:

say map{substr'   | |_|_ _ _|',vec('0123456789abcdef',$'.$_,4),3}split!//,"@_"for 0..2