Any good tutorials on how to make an OS

Here are some links that have appeared on HN in the last several years:

6.828, MIT: https://pdos.csail.mit.edu/6.828/2018/xv6.html

CS140, Stanford: http://www.scs.stanford.edu/12au-cs140/

CS194-24, Berkeley: http://www.cs.berkeley.edu/~kubitron/courses/cs194-24-S13/in...

Baking Pi, Cambridge: http://www.cl.cam.ac.uk/freshers/raspberrypi/tutorials/os/

OS from Scratch, Birmingham: http://www.cs.bham.ac.uk/~exr/lectures/opsys/10_11/lectures/...

more in HN: https://news.ycombinator.com/item?id=8380822

OS Development, RIT Stockholm: http://littleosbook.github.io/

more in HN: https://news.ycombinator.com/item?id=13258063

CMU, UMD, MIT, Stanford, Harvard: https://news.ycombinator.com/item?id=4834008

OSDev.org: http://wiki.osdev.org/

BrokenThorn: http://www.brokenthorn.com/Resources/OSDevIndex.html

bkerndev: http://www.osdever.net/bkerndev/index.php

JamesM: http://www.jamesmolloy.co.uk/tutorial_html/

LinuxFromScratch.org might be up your alley, though I suppose it's still one level higher than actually writing your own kernel.