Sources for the resources I used:
https://free3d.com/3d-model/45-acp-smith-and-wesson-13999.html
https://free3d.com/3d-model/sphere-bot-basic-50922.html
https://free3d.com/3d-model/black-floating-robot-48354.html
http://www.orangefreesounds.com/walking-footsteps-on-metal-surface/
http://soundbible.com/1359-Small-Fireball.html