Designed for my fork of a  #QuadRap   search on G+.(only the cross !)Print four of these parts for one cross. Calculated space 14mm between the parts.(Roller plus one spacer on each side)The picture is copied from Mauro Manco!Have to add HexaNut and roller for the carriage!Done, enjoy it.Be careful, the matrix for rollers and screws is 50mm !!!I use two 695 zz ball-bearings for each roller.So you can fit the inner roller with m5x25mm polyamid-screws.Thx to Marc Schönfleisch,Shauki Bagdadi and Mauro Manco fortheir inspiration!