The hardware part is over but now it's time to switch your head into programming mode: up to now, you can just control your mousepad by loading sketches using arduino IDE, which it's not that bad if you have a lot of time to waste editing each time multiple lines of code: better to have a software running in background on your computer, which talks directly to Arduino via serial communication.

Luckily for you, I open sourced everything about this project so on my Github repository you can find the arduino firmware as well as the software to run on your computer: of course if you want to try doing everything by yourself it's perfectly fine, in fact this is the most boring part of this diy, so if you don't feel like doing it then no problem. PRs are welcome, of course! the program is not finished yet, in fact it can just do basic things like setting individual leds or with a certain layout but I'm a student and I don't have much free time :S

In the pictures you can see some tests I did during the process of building everything, if I had to place them on a timeline made of these DIY steps then I would choose to insert them on step 8 but I decided to not include them because, you know, they are just coding and testing, including studying solutions to have the best edge lighting as possible (like, varying the number of leds and the distance between them to get a uniform light without mixing too much the individual colors). I also included a picture about an attempt with the oled screen to display real time satistics about my computer (cpu, ram usage etc.) and some others about the development of the user interface.