I designed a new Printer based on the GRR PRotos metal frame. The intention was to remove all design weaknesses I found over the last 1000 hours print.... and it works more than perfect. Replaced the wobbly 8mm stuff with stable 10mm linear guides for all axes. Z axis is prepared with precise 8mm trapezoid thread Special Cooling system for perfect PLA Printing fits for standard GRR Hotend. enhanced Hotend version for E3D Nozzles and bigger Heatblock for rock solid extrusion temperature special Extruder adapter for direct extruder with very easy Filament transporter. optional a 5:1 gear Nema17 can be mounted but my experience is that the gear needs higher Voltage than 12V !! otherwise retract will cause huge trouble fits also for all Hotends with 16mm mounting diameter. The pictures are showing the rest :) The printed Hand shows how precise it works - the diameter of the fingers is between 1.2 and 2 mm.. printed with a 0.4 nozzle !! Sorry but the parts are not for download but if you contact me I will make you an offer.