Old tape players are abundant, and cheap. Many have solid speaker sets, perfect period styling and design, and handle-equipped portability. So, what to do with 'em? Play music through them! Oh, tossed your mixtape collection in the late 00s? Then, I guess you gotta make that music yourself.
Austrailian maker "lonesoulsurfer" came up with this fine technique of turning a tape-playing boombox into a portable guitar amp. He shows you how to hack the tape heads themselves to deliver the signal to the amplifier and speakers. Pretty neat idea.
Check out the full tutorial, with video, on Instructables: Hack Any Tape Player Into a Guitar Amp