Switches: Gateron Clear 50g (w/ Super Lube PTFE and films)
Keycaps: ePBT Blanks
There are several guides on how to build the keyboard. However, there are some things to keep in mind, e.g., some of the Corne PCBs use SMD components that you need to be a bit more careful with, some recommend to solder at around 270 degrees Celsius, whereas with through hole components at 350. I accidentally destroyed a pad and had to fix a bodge wire to get the failed switch to work.
The flashing process: cd to the qmk directory and create a new keymap for your user for the Corne keyboard; cd to where you have your json keymap file, created with QMK configurator; create the keymap.c and copy it to the keymap directory; stop the modem manager; flash the elite-c and then the pro micro.
qmk new-keymap -kb crkbd
qmk json2c crkbd_rev1_legacy_dhm.json > keymap.c
cp keymap.c ~/qmk_firmware/keyboards/crkbd/keymaps/HanssonMagnus/
systemctl stop ModemManager.service
sudo make crkbd/rev1:HanssonMagnus
sudo make crkbd/rev1:HanssonMagnus:dfu
sudo make crkbd/rev1:HanssonMagnus:avrdude
Some changes you might want to do before you flash are:
The layout of the Corne keyboard is nice. Even though I use the same keymap on other keyboards, the slight column stagger and the thumb keys make it pleasant. The fact that the microcontrollers are mounted on the top side of the PCB enables shorter stand-offs for the sandwich case and thus it becomes a bit slimmer.