Since it's the third time someone asked me for a small Debian based OS to put on a usb disk, I decided to give it a go. In short, there isn't a small Debian based mainstream OS to put on a small flashdrive. Well, there are, but you will not have much space left on the device if you're going for mainstream shit. I'm thinking gnome,xfce4,mate, cinnamon etc.. You might be ok if the drive is like 64 Gigs, but let's imagine you only have a 32 Gig one.Imho, the best way to go is going for a Debian netinstall. Stock Debian,no crap whatsoever. Once the core is installed it's up to the user what he will install as the gui to be used. The smallest ones would be tiling managers of course, but far from many want that. Most people would opt for a more traditional interface. It's obvious it's totally redundant to install one of the usual DE's on that so one might one check light DE's such as icewm, jwm etc.. Me personally, I'm an openbox guy for the simple reason that's it's leight, fast and amongst THE most, if not THE most customizable one. So, here's an example. To begin with, it's a Debian stable netinstall. Here's what I put on top of it. Lightdm, openbox, obconf, obmenu, obkey, tint2, volumeicon, spacefm, lxterminal, Iron browser, Palemoon, geany, abiword, gnumeric, galculator, xdotool, mtpaint, feh, htop,conky, gnome-writer, catfish, orage, gcolor2,audacious, mpv,gnome-alsamixer,speedtest, gparted, synaptic and some which I forgot (won't be much though). It's highly script driven and two things are not installed. Being gimp and libreoffice (which I never use). So, all this results in a whopping 2,92 Gigs on a 27 Gig partition. And on this rig it boots around 78 Mibs. So, let's say you add gimp to it, I'm guessing something like 3 Gigs. It must be said this is a desktop. So a wireless setup might add an additional 150 Mibs. Like I said, you could get smaller,but not much.