Introduction: Lego Galvaknuckle Instructions
Built from Lego's. Credit goes to ZaziNombies on Youtube. Go check him out, cause he has lots of other cool zombie weapons built from Lego's. If you want a good description, go to Zombiekiller-93's Instructable channel and look at his Knex Galvaknuckles.
https://www.instructables.com/id/Knex-Galvaknuckles-Instructions/