About this 3D model

MaxGlide is a itemhttp://www.thingiverse.com/thing:84142 I loved the idea but i wanted smoother action so i put bearings in it. I bought them thru Mcmaster Carr, but here are the dimensions you can get probably anywhere... http://www.mcmaster.com/#60355K861 3/16 for shaft diameter id. OD 1/2inch, R3 bearing number. anyways you can take the half inch hole and modify it if you would like but i built it the same as is his instructions other than adding the bearings...