A classic lego-like brick with knobs on every side.
Inspired by ffff.at Free Universal Construction Kit,
and the fact that Lego's brick patent is over.
Detailed dimensions and proportions of a classic Lego brick can be found here:
enjoy / make / share
It prints nicely in 10 minutes without support.
Successfully tested in PLA on an Ultimaker running Marlin.
Sliced with Cura