The physical interface wasn't the same for every laptop, but with a common backplane it should be possible to make a seperate docking connector daughterboard for the most popular laptops taking up cupboard space.

I would love to collab on an open-source dock that turns laptops into servers :)

You could probably use only one USB port on the laptop and integrate a hub into the case. But for ethernet, audio, and HDMI, you'd probably need cables. The nice thing about cables in the box is that adapters could be used. If a laptop comes with VGA out only, that can be adapted to HDMI. If there are separate audio out and in jacks, those can be combined with an adapter. If there is no ethernet jack, it could be added with a USB network card. There are also adapters for laptop power supply cables for the C13/C14 three-pin interface.

So a lot of work can be done inside the case by the person building a desktop/console/server out of a laptop. But no one is selling a universal case with a backplate. And desktop cases are difficult to work with because they expect a backplate from a motherboard.

Really, the product could be just an I/O backplate that mounts to standard ATX stand-offs/screws and takes extension cables, plus something to regulate fan speeds by temperature that also has fan headers. The power button might be a challenge for the builder to solve, but with very minor soldering, most power buttons integrated in any case would work.

In this case, there would be no need for a universal case because I'm repurposing everything in the laptop "as is" except the screen.

I also have a couple 3350's where the power port is way too loose to use them for much of anything. I need to see if that's replaceable.

I had an old dell laptop that had a double-high pcmcia port and I inserted two xircom realport LAN cards and had a very nice router with three NICs and no dongles.

But these days there are often controls in place to cut off power if things look bad (battery getting too hot, mainly) so things are more likely to die on their rather than setting fire to themselves and anything near-by.

I gave up on worrying about those details - just installed ProxMox, set it on a shelf in the basement, moved on. Works great for the tasks I'm running.

I was even thinking about how much mileage could one get from a rack of old laptop logic boards. Gaming laptops sold for parts are much, much cheaper than "real" server hardware. It appeals to me because of the reuse aspect as well.

Holds true regardless of your workload :) Imo sounds like premature optimization.

No need to remote into it when you can just open it.

Though take care with the batteries. Left plugged in 24/7 some turn a bit fiery after a time, or just fail in a way that takes out the device at an inconvenient time.

Some remove batteries from laptops used this way for that reason, though that throws away the built-in-UPS benefit. Another option to mitigate the issue is a timer switch that disconnects power for an hour every few, this works well while the battery still has enough life in it at all.

If you are a smart-home-hacker you could rig a controlled plug up to the battery state so you can flip power back on/off when the battery hits a certain level, rather than relying on a fixed time period, though I'm unsure whether that is worth the effort in terms of preventing potential faults and preserving battery life (IIRC charging up to 80-to-90% and discharging to ~40% is considered optimal for prolonging the useful life of modern batteries?) or if it would “just” be an interesting nerd project.