As in, channels where the presenter is laid back, calming, and the content is slower paced and chill. My go two examples are LGR for retro computer stuff, and Hainbach for experimental tape music.
I mostly watch guitar luthiers on youtube nowadays as a background for when I do stuff like washing dishes and such, so I don’t want to listen to people yelling.
My favourite channels are twoodfrd and Doug McCormack for this reason exactly: they’re laid back, constructive and politePask Makes - Australian wood- and metalworking guy who does the most elaborate and intricate things with absolute chill.
Dashner Design and Restoration - also woodworking, finds old and neglected mid century modern furniture at thrift stores and restores them beautifully.
Maybe tangential but FutureCanoe - meme-y cooking channel, super relatable and relaxing mostly because his voice sounds like existential dread.
Most of what I would have suggested has already been posted by others, but I can say Kruggsmash’s Dwarf Fortress stories do this for me. The Waddlesquash/Kingdom of Autumn series he did (with the pumpkin mod) is particularly laid back, but even the action-heavy series are calming to watch/listen to.
Pretty much exactly Bob Ross if he were a nice Canadian lady doing nails…
Bill Hammack - TheEngineeringGuy
All manner of engineering gadgets and phenomena explained clearly and calmly.
All licenced as CC BY.
LockPickingLawyer
Steve Wallis (Camping With Steve)
Math Queen
City Planner Plays is quite literally the Bob Ross of city building games. He uses his actual professional knowledge of city planning to build really creative and compelling stuff, and he makes it seem easy enough that you want to try doing it yourself. He has commissioned a library of chill lofi beats that he plays in the background of all his videos, which adds to the vibe immensely. And on top of that, he seems like a sincerely pleasant guy, just having fun doing a thing he enjoys doing. It’s an absolute gem of a channel.
Ogmios - dude drives carefully around London, is nice to pedestrians and other traffic, and has a calming voice.
Cathode Ray Dude
Bernadette Banner - Historical handmade clothes and sewing tips
The Lock picking lawyer. Too bad the videos are so short; he has a very soothing voice.
And, of course, the OG Bob Ross. I do oil pastel drawing, and often take inspiration from his works.
Click spring for watchmaking. It can take 6 months to do a single build and they’re insanely intricate.
Food Wishes with Chef John. Very fun, laid back, and dare I even say informative if you’re into cooking.