I built one...
(bass shakers were on sale for $24 the other day @ parts express)

well... my couch is total junk... it looks like the manufacture took old pallets apart, and used the pieces to make couch frames

so I was able to mount the shakers on the lower frame (if you can call it a frame) so it shakes the one's butt, but not one's back...

suggestion for making your own ht couch with bass shakers... make sure you have a good frame on the back section for mounting the bass shaker.