My 3rd custom made PC case. It is quite small at just about 9 litres , but still capable of fitting some serious hardware. It can fit GPUs up to 23cm and an 120mm AIO.

Not being my first custom case, building it has been an much easier task. In particular because of be layout being quite simular to my first case:
https://builds.gg/builds/battlebox-1-0-sff-gaming-rig-10898

But there have been challenges too.
Instead of using an back io panel from an old PC case, I modeled one myself using CAD and 3D printed it. It took some time to get it good enough.
I have used 2 mm sheet aluminium instead of 1 mm. In order to be able to bend it I needed some kind of tool. But this kind of tools being expensive, I opted to build it on my own at the company I used to work back then. It wasn't perfect and required a hammer some brutality and a vice, but it worked.
The rest went pretty much straight forward... until I realized that I hadn't though about how to mount the top and bottom panels and I haven't had a clue what to do about some front I/O panel.
So, for the top and bottom I figures out just to use some angled aluminium profiles.
I ordered the front I/O from Corsair, after finding out, they are selling them separately.
The last things I've had to do then, was shorten all the cables from the PSU and make some cableing for the adressable RGB-strips

So, there it is.
Hope you like it