Maim
I'm using maim + slop to get REALLY nice and fast screen captures via PrtScrn key in i3. When I grow up I wanna be Taylor! love you buddy...
But Ubuntu's 17.10 maim package is busted. Compile it!
cd ~/apps && git clone https://github.com/naelstrof/maim.git && cd maim cmake -DCMAKE_INSTALL_PREFIX="/usr" ./ sudo apt install libjpeg-dev libxcomposite-dev libxrandr-dev libglm-dev make && sudo make install