The customizable spool holder of peka (which in turn was based on the one from Luchador) had a too small gap to fit the wall of my RepRap Neo, when printed with Simplify3D. So this spool holder has a second configurable parameter, the gap.The attached STL is for a length of 80mm and a gap size of 2.8mm which turns out to be a gap of 2.4mm when printed using Simplify3D and two shells. For different lengths and gap sizes, use the Customizer or edit the OpenSCAD file.