I'm looking for a "modular" modular case.

I have roughly 12 running metres of Eurorack (about 2400 HP), spread over several cases, plus a couple more metres of unracked modules. Rearranging anything and interchanging modules between racks means unscrewing modules, unplugging power, moving, replugging, screwing. So:

Is there any rack system built from cassettes and slide-in frames, so you can completely rearrange your rack in a few seconds? My searches came up empty.

In the meantime I had an AI assistant design one to my spec. The concept:
• Each slide-in frame carries power. A cassette is a complete 3U unit with its own rails and busboard, and it slides into the frame from the front, makes contact at the back and locks at the front.
• Cassettes go in and out in seconds. A lever on each side locks the cassette and also ejects it, no thumbscrews.
• Power goes through spring contacts on both sides, like a cordless drill battery. Standard gold-plated battery connectors, 5 A per contact, +12/-12/+5/GND, everything doubled.
• In theory it retrofits into any existing case: nothing sits higher than normal rails, the row pitch is 3U plus 1 mm, and you can make it any width in HP.
• Space-efficient: you lose less than 3 HP per side (cheek + gap + frame plate = 14.5 mm).
• Frames bolt together sideways and vertically, flush, nothing sticking out. Angled brackets let you stack rows at 30, 45 or 90 degrees, so a flat-to-vertical console needs no wooden cheeks at all.
• No fiddling with busboard cables: with the cassette out, the busboard is fully accessible from the back.
• Parts: 3D-printed cheeks, lever and frame plates, standard aluminium rails and L profiles, two small PCBs for the contacts. Nothing exotic.
Is there a case manufacturer offering something like this, or even a more mature, tested solution? I'd rather buy than build.

For anyone interested, here is a 3D model of the idea (interactive, rotate and zoom, slide the cassette in and out):
https://claude.ai/code/artifact/d3cbaf71-6c02-4657-91d7-08561216aa77
It's a design only at this point, not finished and nothing has been printed or tested yet.

Thoughts, ideas, things I'm missing? I think this could work.

Happy patching!

Could it work? Absolutely. The basic idea has been used for all sorts of computer/data applications for years. It's also not too far from the concept of mounting your modules in standard 19" rack hardware.

But I'm not really sure what advantage this gets you*. You're not able to move individual modules around easily, instead you move them around in groups installed in fairly large "cassettes". At that point, there's not much functional difference between a "cassette" and a small powered case. You can stack small cases to make a larger rack, and you can use them individually without having to plug them into to a larger apparatus. I wonder if 19" industrial racks or stacking smaller self-powered cases could acheive the same goal, but maybe this suits your needs better, so long as it was designed & fabricated carefully it would work.

I think you could improve this design by replacing the L-angle with perforated sheet metal bent to shape. That would be stronger and would provide electrical sheilding while still allowing airflow. I also think making the cheeks and the levers out of aluminum would look a lot better and be more durable, that little detail would make this look like something out of an aircraft or spaceship which I think would be very cool.

• I fibbed a bit when I said I couldn't see any advantages. I do think the easy access to the rear of the busboard is an advantage. My biggest gripe about re-arranging modules, especially with a large case, is that sometimes it can be a real hassle to plug/unplug modules from the busboard. Having access from the back is one way to solve that problem. However, if you're re-arranging your modules in groups (cassettes or individual powered racks), how often are you having to deal with that problem anyway?

I've been thinking about a different challenge: If one has a very large system, how to access a lot of modules without having to stand up-and-down so much. One idea that came to mind was inspired by old-fashioned lecture halls which had flip-around double sided chalkboards. A teacher would write on one side, when that was filled up and they needed more space they would flip it over and write on the other side. If at any time if they needed to refer back to what they originally wrote it just took a second to flip the board over again. A rack could be built like this: Imagine taking two racks, attaching them together back-to-back, and then having a central axle about which this entire assembly can be flipped around quickly and easily. That central axle would be hollow and would contain power cables & breakouts. The only major disadvantages would be:
a) you couldn't simuntaneously tweak modules on opposite sides of the flip rack
b) patch cable positioning could get complicated

I don't think these are killer disadvantages. Problem a already exists for large systems. Problem b can be dealt with by providing breakouts built into the rack. Some would go front-to-back between the two faces of the flip rack. Others would go out from the flip rack, through its hinge, to allow connection to modules elsewhere in the system. I'm imagining the finished product to look like an upright piano. It would sit on the floor, have 3 or 4 rows of modules oriented mostly horizontally, sort of like a desk or a standard keyboard position. These would not "flip". A vertical section would sit above, with most of it being the flip rack. A robust latch (foot operated?) would allow this to unlock and be flipped around. Part of the vertical section would be stationary and would contain the breakout connections as well as more space for modules that would not flip.

Of course, it's not ideal that you can't tweak both sides of the flip rack simultaneously. However, the trade-off is that you have easy (albeit not perfect) access to a lot more modules in the same amount of floorspace, and you absolutely can play that many modules simuntaneously thanks to the breakouts.

@Replicant2501

Thanks for the feedback, and for the honest take.

On the advantages, here is where it comes from for me:

I have a huge rack in my studio and another huge rack at home. Every time I buy a module I go back and forth about which rack it should live in, and whichever way I decide, sooner or later there's the moment where I sit in front of one rack and wish I had that one module from the other. With cassettes, that's a few-seconds move instead of an evening with a screwdriver.
And the time-consuming decision part disappears completely: which modules do I pull to make room, how do I fill the gap that leaves behind, and what else has to be rearranged to make it all fit.

I've also often wished for a very small rack to learn a single module in isolation. Ideally not sitting in front of a monster system, but small and tidy on the desk in front of me. I picture a little two-slot rack: one cassette with a handful of essentials, the second cassette holding exactly the module I want to dig into. Swap the second cassette, learn the next one.

And a few friends occasionally bring parts of their racks over when they visit. If their cassettes are compatible with my frames (which is what they're aiming for), it becomes very easy to bring whole cassettes along, or to lend them back and forth for a few weeks without anyone unscrewing anything.

So yes, functionally a cassette is close to a small powered case. The difference is that the "case" part is shared and stays put, and the moving part is only what has to move: rails, busboard, modules, no PSU, no cheeks, no cables to plug.

Your points on the hardware are well taken. Bent perforated sheet instead of the L profiles is a good thought, stronger and gives shielding and airflow in one part. Aluminium cheeks and levers would definitely look and feel better; I've started with printed parts because every dimension is still changing, but that's exactly the kind of upgrade that makes sense once the geometry is settled.

Your flip case idea is fun and creative, I like the chalkboard picture. How well it can actually be built is another story. :)

EDITED Sep 15th, 08:53

I totally understand why you would want to move modules around. I also know what you mean about having a mini rack for focusing on a specific module without having it tied to your main studio. I have basically that same setup: a big rack in my studio, and a much smaller portable case I can carry around wherever if I want to concentrate on a specific module. I equipped it with some basic utilities and a few leftover modules that I bought when I first started out but have since retired from my main studio rack. It's about half full so there's plenty of room for testing out a new module. Also, it was a handy place to put modules before I completed building my full-size case.

I think my biggest hangup is the size of the cassette in the image, though the more I think about it it's a difficult balancing act. The larger the cassettes are the less advantage they have compared to individual powered cases. A large cassette forces you to swap many modules while you may only want to swap one or two, and it's actually a bit more complicated for traveling. A powered case can go anywhere that has electricity. Traveling with a cassette requires you to make sure your destination has a cassette-ready case waiting for you. You can circumvent that problem by bringing your own case, but at that point the cassettes are superfluous. The smaller the cassettes are the more interesting the module-swapping possibilities become. The design you created could easily be made narrower to scale it down. However, the smaller you make the cassettes then the more HP you give up in a large rack for the space taken up by the latches. And of course the cost goes up because you're having to buy more cassettes. I think determining the sweet spot in the cassette size is going to be all-important.

I totally agree that it makes sense to 3D print these before having anything machined, if it's one thing that 3D printers are good for it's this kind of prototyping. Also, now that I think about it, you could probably also make the cheeks of the frames out of bent sheet aluminum. Modern sheet-metal forming presses can insert hardware like threaded inserts, studs, standoffs, etc automatically so companies like Protocase, etc, could make those quite economically.

I am sure I could build a nice, workable, "flip" style case. The problem is that it would be a lot of work as there are a lot of little details to worry about. The latch on the flip portion needs to be well thought out because if it feels awkward to use or doesn't lock securely then it would ruin the ergonomics of the whole thing. Commercial-quality door latches seem like a good choice since they are meant to handle high duty cycles, but where exactly to locate them and how to control them? Where to put the lock handle and how to make it work? And there also needs to be some provision to balance the rack because if it ends up wanting to flip one way or another due to gravity that could make operation difficult. Perhaps operating the latch simultaneously applies a friction brake to ensure it doesn't move until you can put your hand on it? Maybe have some kind of rotary damper on the axle to limit its rotation? I'm sure I could address all those things, but it would be a complex, expensive project that is ultimately a gamble in the end. I could foresee it being perfectly functional but awkward to use, and I'm not sure I'm willing to roll the dice on that yet.