I want to expand my Digitakt with modular (Techno/industrial based).
Do i need other modules for cv, gate, clock, ... to work properly?

the answer to that is probably no - at least to start with... but you'll probably find you want more very quickly... and then run out of space, so...

Any case idea?

yes - ignore case for now - work out what modules you need to achieve what you want from your modular, then work out what modules you need to support them - mixers, vcas etc and then add about 20-30% for expansion - then find a case... my advice start with a mantis...

"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia

Utility modules are the dull polish that makes the shiny modules actually shine!!!

sound sources < sound modifiers < modulation sources < utilities