I'm just starting out in the world of modular, and to be honest while it's been confusing a lot I think I might have made a rack that functionally works, but I'd like to check with some people who know things first! I'm a classically trained musician, so getting into this synth world is an exciting way to find new forms of expression, but also as a steep learning curve.

The main idea behind this rack is I want to build it over time, I don't expect it'll be finished for a couple of years, starting with the bottom row and building up. The end goal is a modular that will be a stand-alone synth voice I can play with MIDI keyboards, as well as being able to process external audio for effects, like my electric bass. I tried to design it so the bottom row is a full modular synth voice, and the top is a second voice and effects rack, with some sequencing that will let the whole thing play on its own.

I'm also trying to be quite DIY with it, partly because it should bring costs down and also because I really want to be involved in the creation as much as I can. It'll also help me bring some family who don't really get the whole 'synth thing' into my world a bit, since they work with wood and electronics a bunch (I'll be making my own case as well).

Thanks for any advice!

Well, that's certainly a pile of modules. But that's ALL it is. You're missing things that can make this build stand up and howl, such as attenuverters, submixers, logic and other clock modulators, and so on. There's also a lot of audio sources and modifiers, but the modulation sources are pretty lacking. And WHY are you taking up 8 hp in a small build like this with a BUTTON? Put something useful in that space!

Also, that's the wrong sort of input module for external signal processing...it's JUST a preamp. You need something with an envelope follower to really make that work optimally, so that you can do things like opening/closing filters with your volume level, etc. And two Distings? If you have a problem with menu-diving, especially on a minimal-feedback UI, you're really going to regret that. I like the idea behind the Disting, but I think the implementation is cryptic and crummy...not anywhere as immediate as you'd expect from a modular synth.

One more thing: if you're all about the DIY thing, DON'T build your tile row for Intellijel spacing! You'll find a much better selection of tile modules, including a pile of DIY ones, if you stick with the "original" 1U row spacing.

This is why, when I did my "classical training" in theory/comp (which was a bit looser than hardass conservatory definitions of this, mainly because where I did my undergrad was far more open to things other than the typical "serious music" and what that entails), I thought it was CRITICAL to get some audio engineering under my belt, in addition to my required electronic music coursework. These sorts of things aren't what I'd view as "electives" anymore; composers in this century need to know how to work with this technology, given what's been replaced by it. F'rinstance, I haven't scored anything with a pen since the mid-1990s...using scoring suites is so much better, plus I can check my work instantly; previously, doing a playthru check would entail sticking paper in front of a bunch of players who'd probably not looked at their parts until that very minute...in short, a real nuisance! Composers these days ignore tech, popular musical forms, etc at their peril!

Yeah, I agree with Lugia. You're on the right track, but you've got some modules that might not be the best use of time, space, and money. This kind of reminds me of my original plan, which changed drastically as I started actually putting it together. My advice would be to go slow. Start with a sequencer (doesn't have to be Eurorack, but could be a Beatstep Pro or Korg SQ1), something like Plaits, Maths, and Veils. Then see what you are missing. Need a filter? Buy that, and then repeat. Need a big a** button? Buy that, and then repeat.
Unless you really need the phantom power of the Little Mikey, the Doepfer A-119 is an external input/preamp with envelope follower that can be had for about $70 used. I kinda hate working with Disting, but adding one to a small rack is a decent idea. It will help you understand a bunch of different functions (albeit, not in a very fun way), and give you some ideas for the next fully featured module you should buy.
Have fun and good luck.

DIY dos not necessarily reduce costs

you need to look very carefully at your mixing solution - it won't work - the frap tools mixing solution needs a minimum of 3 modules - for a single channel mixer - the module you have included in the rack is just the master - no channel inputs!!

I'd rip everything out and start again - put back in a single voice (a minimum viable synth) and work out how you would play, modulate effect and listen to that voice - think about how you will patch it - consider utility modules

then add another voice and do the same exercise - utility modules become more important

how do the voices interact? how will you cross modulate? how will you combine modulation sources to make more interesting modulation?

and then add another voice - repeating the same exercises... utility modules become even more important

you will probably need to replace a few modules along the way

you case should now be full - or nearly full - aim for 3 or 4 voices (max) in a 6u case is enough