Building my own Kosmo case, in the video it says 20cm deep but I was wondering if i could get away with 10cm deep? are some modules crazy big? they don’t seem to be since the PCBs are parallel with the front panels.
I’m mounting the Frequency Central on a front panel so that probably isn’t an issue.
That depends…
It’s you case… i’d leave more space for future needs
True of Sam’s modules. But some other peoples’ designs go deeper, sometimes with perpendicular PCBs. My first Kosmo case was too shallow for some of my own homebrew, my second is about 20 cm deep.
I’ll go for 20cm then, thanks!
I will say 20cm is a completely worry-free depth. You can play it lying down, standing up, etc. You can swap power supplies, put in weird breadboard modules, etc.
Weird modules is the deciding factor here 
I’m not one to give advice here (I’ve hung around and investigated some weird concepts, but haven’t actually produced anything.) It does still seem to me that for static synths a second hand bookcase makes an excellent mounting point. You can use velcro, screws, panel tacks or whatever to mount modules, construct cheap plywood or cardboard baffles to adapt different module panel sizes to work together, and the depth is usually adequate.
For portable cabinets I would defer to our host Sam Battle and others who have immense experience taking quite delicate modules on tour, and many soldering iron scars to attest to their achievements in construction. I do have to admit to some personal regrets over my failure to gather up various roadworthy amp and speaker cabinets left on the street by neighbours who needed to dispose of their old DJ kit. There’s a fair amount of suitable cases around if you’re looking and don’t mind the challenge of adapting what’s available.
Good point, I wanted to use wine boxes but loamy is just too big! (Or I just don’t drink enough wine) opted for a wood cutting service for a single layer 75cm across inside so it fits inside my IKEA shelf, cost about 80£
Ive gone for 15cm depth on the sides, indented the modules by 2.5cm and got my backing panel and buss boards mounted inside and so far not ran into troubles yet, it is a bit of a mess though =)
But some other or DIY ones might be deeper as AO said
my Kosmo cases are 30cm deep and eurorack case is 20cm deep . more than enough but I didn’t mean for them to be mobile and I have them stacked 2 and 3 high so I needed the stability of a deeper case . and yes I am lucky enough to have the room to .
My cases are also 20cm deep with the power supply inside and that’s good for me.
Some here like some modules with panels 2.5 or 5 cm wide to save space, but in these cases it is often necessary to install the pcb or stripboard perpendicular to the panel and some can go quite deep in the case.
Mines approx 10cm because I was repurposing an old photo frame. It definitely feels cramped with the power buss boards and ribbon cables.
A work in progress
Another factor to consider is how easily the case will tip over. My main Kosmo case is probably about 10-15cm deep and three rows tall and it’s a tippy bear to deal with. I’d go 20cm if (when, I’m sure,) I were to do it again.
Good point! I was only going for one row but if it’s not square on the sides it might tip!
I’m using the flightcase cover of an old compact organ. There’s about 7 or 8 cm between panel and back.
I like how compact it is but making power connections is a pain. I had to make busboard panels that i can pull out to make connections.
Also, the arcade buttons i’m using just barely fit.
I’d go with 20 cm for my next case.
For the people with shallow cases tipping over: it might fit on a guitar stand. I had to bend it a little bit to make it fit but is quite stable