Enough with the learning let’s get our hands working and build a custom ICSP cable to program/bootload an Arduino, an ATMEGA328P (chip used in Arduino UNO) , or any other AVR microcontroller. Things ...

This Arduino ICSP programmer has been made from Alumide, a strong plastic with aluminum fibers. The cover is made from translucent POM, illuminated by three rings of in total 27 LEDs.

Speaking personally, I’ve made custom systems around an ATMEGA328P chip which remove the bootloader, d1 and d2 lines, and the USb adapting FTDI chip, you can program the arduino chip over ICSP ...

Arduino microcontrollers have added Python to the range of compatible programming languages. Others can be used, and not just Arduino's own IDE app.