Hello, i am looking for a way to insert new caracters on my keyboard since january but i cannot figure out how I can proceed. I tried a lot of things.

Eg : programming the keys ctlr-e to make a new letter Ɛ, ctlr-b to make ɓ, etc.

Thank you for your help. wang

Hi!

Have a look at Xmodmap. It is based on the XServer but used in Wayland too and the easiest way to (re-)define keys.
Ctrl+Key won't work as Ctrl is not that easy usable as single-modifier to generate characters. It is used to send control sequences.

If you need more control or want to create a full custom layout, have a look at /usr/share/X11/xkb/symbols/. If the graphical environment should see this layout you have to edit the evdev.xmls too.