The semi modulars usually have some sort of side panels which are detachable. For the Neutron I timbered some fitting panels out of beech wood and screwed it on top of my rack. Saves precious rackspace and you can still patch it as if it were in the rack.
If you really only want to to tip your toe into the modular waters, there is the Tiptop Audio Happy Ending Kit. 84hp, you can mount it into a rack, a uZeus power-module with 1000mA is included. The company-thou-shalt-not-name with the big B offers a similar solution for a few € less.
Or, and for me that's the way to go, build your own case. There's dozens of videos on YouTube with quite detailed instructions, and if you're not completely useless with a jigsaw, it's a cost-effective and fun alternative to prebuilt solutions.
It might be overkill, but the Westlicht Performer does that. I use it all the time to sync my modular to my Boss RC-5 Loop Station.
This is exactly how I got into modular, although my entry-drug was a Neutron. I thought a MI Clouds would satisfy my effects needs, so I got a Behringer Eurorack Rack (includes a power module) and stuffed it into my 19"-studiorack. Another filter would be nice, I thought. So it started ...
Well, as Jim said, several modulation and utility modules later the rack was full and I built a 6u 104hp-case out of beech wood, screwed some rails into it and continued my journey. And yes, it's expensive, but there are ways to keep the budget reasonable. Always check the classifieds, get clones where it's possible (and ethically justifiable) and think about DIY.
I don‘t own a Volca Modular, but I successfully synced my Beats, Bass, Keys, Sample and FM to a Keystep. In the Keystep-MIDI-Software there is a section where you can choose different sync-options. As Jim said you have to set it to the PPQN the Volca expects. If I remember correctly there is a KORG-setting, this should be the one.
My first case was a 84HP in a 19"-rack as well. It didn't take long to fill it, as was to be expected, but we all have to go down this road as it seems ...
I built my second case (6U 104HP) out of beech wood and bought rails separatedly. I use a TipTop uZeus as power supply. I had a lot of fun building the case, it was not difficult at all and came out significantly cheaper (and nicer ...) as the Mantis. We all know modular is not cheap, but the prices for the cases are far beyond reasonable IMHO.
While I still don't get my head around Clouds, the Miverb, included in the alternative Parasite-firmware, is in my opinion a fantastic reverb. Emilie discontinued Clouds, but there are clones around by After Later Audio or Tunefish Modular.
As for mixers, the Doepfer-line offers fantastic value for your money. If you like to DIY, you might want to look at the Befaco STMix as a kit. Not the easiest build for a novice, though, the layout is quite dense.
