Not quite from scratch, but you have 60-80 different modes, each with 1-2 adjustable parameters by default, and even more in the show builder. You can use these as building blocks and create an almost infinite variety of patterns.
If you know how to use complicated software/hardware systems, you might be interested in our creators core system and open-source software that gives you way more control. This system is for technicians and we do not provide technical support for it. It is very DIY, but also very powerful and you could truly create modes from scratch and much more. You can find out more about the creators system here.