Recommendations for easy modable flashlights

I am looking for cheap flashlights that are easy to modify to my needs.
What is needed are flashlights with a side and tail button, tail button should turn it on/off and side button for functions. Multiple side buttons would be a huge bonus!
Since I am quite new to modding flashlights I have no idea how hard or easy these flashlights are to take apart and modify, so some that are beginner friendly would be best.
Second requirement would be either a controller with a chip that can accept custom firmware (attiny is probably best because I already am quite familiar with arduinos) or an easy replaceable one to a driver that has this option.
Not sure yet how the side buttons are connected to the controller, most custom controllers I have seen don’t have extra exposed control pins. How do they work?

I have ordered a couple ThorFire TK15 since I came to love these flashlights and will start to replace the LEDs in them and take a look at how the controller is build.
Are these good to work with, has anyone modded ThorFire flashlights already and can give me a feedback on how they fare?

Thanks from a beginner in advance :wink: