I'm looking for a rack that can i use it with and without a computer, with polyphonic (4 voice) capability and a small drum and fx section, i hope i nail that, but i'm a noob so i need the help of the community to understand if i'm making some mistake.

Seems good Tototun. u should be able to do what you want. 4 voice poly + drums and fx.
couple of things u might want to know: you have an output module which makes me think you want that as a final output but you might want to add a mixer so you can have more sources going in there .
also as for midi be aware that this exists too: https://www.tindie.com/products/hotchk155/cvocd-a-super-flexible-midi-to-cv-box/
so you can have poly midi AND trigger a lot of extra stuff for less money than the yarns.

theres about a thousand ways to design a case that does what you want so i wont give you any advise there its much more fun choosing your own modules i think :D

cheers S

Wow, that midi module seems cool and super usefull, tnks for the suggestion :)

I'll second that! That's a killer MIDI interface for the price, and it brings up a good point: don't always try and put all of the modular's devices IN the rack...sometimes outboard is the right way to go. Like here, apparently!

Other than that, this looks good...but again, I don't think you're going to need a buffered mult. A regular one would be fine, since you're not likely to need to branch one CV out to, say, seven or eight sources and keep them all on-scale. Also, having the other two percussion voices of the 'holy trinity' of kick/hat/snare might be a good swap-out for the Yarns if you go with the outboard MIDI, and you'd still have a bit more space to play with besides if you use small-hp snare and hat modules.