Im also still in the beginning, but I guess the case is way to small except you are totally focused for a certain porpuse and know whar youre doing.
like building a additional FX or noise Box etc for your main case.

I dont know which external gear you want to pair with.

I guess:
1. a midi/cv-interface to pair it with external gear like a laptop or digitakt

like hexinverter mutant brain or others

  1. a nice filter
  2. vcas
  3. distortion / saturation
  4. a minimum of dynamics and processing
  5. lfos

look out for function combos like:

bastl ikarie = filter + drive+ vca

cosmotronic delta is a smal nice vca/envelope

a blackbox external or in the case could be cool for sampling drums if you dont use a laptop or digitakt. - I prefer it over the sample drum.

if you want to explore drums maybe you consider to get different drum modules with different synthesis styles like physical modeling, analog, fm etc - I guess more drum stuff will surely follow.

You need space for utilites like attenuverters
and stuff to scale, shift, offset and mix cv. - you will see what is missing while you are in the process.

I made the hard experience to start with a smal case. Now I pair 3 different sized cases at the moment.

Sure I can alter them for special purposes, but right now, Im looking for a nice all in one rack and to get rid of the others.

Better dont go under 7u 104.
And calculate some trial and error

Greetings

Chris