First off welcome, seems like you're just starting your modular journey.
Some questions to help us make some suggestions:
* What do you mean when you say "sound design stuf or to be able to sequence dubby note?"
* What are your specific musical goals, and what is is about modular that you think can help you get there?
* Do you have outboard gear that you're planning on connecting to this rack?
* How much of your planned rack do you already own, or can we suggest different modules?
* Do you already have your case?
Now, some thoughts. Looking at your rack, I'm seeing a lot of interesting modules that do not feel like a cohesive whole. Did you envision a signal path when designing this rack? I do that often when planning my racks: trying to visualize the signal from start to exit and think of the ways I might wish to manipulate it along its path. That way I start to think about which circuits and functions I'm likely to want.
So, let's look at your system: I'd start with the Euclidean Circuits putting out triggers, which trigger random voltages on the A-149-4, then sends those CV signals to the quantizer (potentially attenuated on Maths first). The CV then goes into v/oct on the oscillator/s and to a VCA. Simultaneously, the trigger would get sent to Maths or the function generator to become an envelope, then into the VCA it goes. Now, we send to the FX. Woohoo! A signal path, and one with some funky randonmess in it, too. Not bad. Of course, we're talking modular, which means that there should be innumerable ways to move a signal around your system to make for interesting results. So, let's start thinking how we're going to make a second, totally different patch from the first on your planned instrument... hmmm. Looking at your plan, I'm not seeing too many ways to move around your system and make workable signal paths.
You need to start thinking about the connecting pieces of your modular synth; the modules that tie things together, manipulate signals, and otherwise do utilitarian things - utilities. These are the modules that allow you better use the "interesting" modules you already have planned. You have a few (Maths, for example), but these should dominate your module collection. These utiltiies will provide flexibility in your patch designs and allow your to create more interesting paths around your system. Of course, there are thousands of utility modules out there, how do you know what you need, particularly when you've never played around with one before to see what it can do? Well, this is where you need to refine your goals for the instrument. Do you want it to be multivoiced? Do you want it to be stereo? Do you want it to be generative or playable (or both)?
Think about the above for a bit; watch how-to videos and read the manuals, and then try tooling around with your plan again. In particular, you may want to look at matrix mixers, sample and holds/track and holds, attenuators/attenuverters, and mixers. Of course, this being modular, the choice really is yours.
Good luck and have fun!
Edited since I'm a stickler for grammar.
