Mars Guy, essentially: what happened on Mars this last ~week or so - https://www.youtube.com/c/MarsGuy

BPS.Space: Dude building model rockets & flight controllers. Just landed a model rocket propulsively, video out soon - https://www.youtube.com/c/BPSspace

Brian Oltrogge/Grunblau: Metalworking, often combining 3D printing with sandcasting of metal - https://www.youtube.com/c/Grunblau

BaxEDM: Dude building his own Electrostatic Discharge Machining-machine - https://www.youtube.com/channel/UCy4kgsAYxcraee8w5SfqXPA