DP-Guide Mod. for the SquareBOT 3D Printer

This is cool upgrade for the SquareBOT 3d printer. Double precision linear guide.
MR12 (MGN12) linear rail (length 300mm)
MGN12H linear block carriage.
Aluminum profile CONSTA-series: 30x30mm, length 400mm (1.5mm thickness,slot 8.4 mm)
Belt: GT2 6mm (110mm) I don't recommend white belts (with metal cord).
Pulley: GT2 20 teeth 2pcs
Stepper motor: NEMA17 18mm shaft
Ball Bearings: 625ZZ x 2pcs, F623ZZ x 4pcs
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2020 version: http://www.thingiverse.com/thing:2136372