Lego Brick (Customizable), and tight snap-to fit

I'd tried printing quite a few of the Lego bricks available out there but tended to find them a little loose fitting. azzeloof's openscad design was pretty good, allowing for full customization of the brick size, although, the bumps, or knobs on top still didn't quite make for a tight enough fit. All I've done is add a variable to the SCAD file to increase the knob size from 4.8 to 4.9mm (you can vary this as you please), the hard work was basically done by Adam Zeloof in 2013.

I've tested th