About this 3D model

After seeing Cunicode's brilliant brick: http://www.thingiverse.com/thing:28240 Which was inspired by http://www.thingiverse.com/uck I figured my sons Duplos need something similar :-) WARNING: Children are dangerous! Erhm, I mean: DO NOT LET KIDS PLAY WITH THIS UNATTENDED! Parts could break off, they might swallow or choke on it, etc. Allow use only UNDER CLOSE SUPERVISION. UPDATE: Added a revised file with tighter fit on the bottom.