I've recently needed a groovemount plate built to reprap wiki J-Head specs and realised all the aluminium plates i had (fitting Arcol.hu, E3D and other hotends) were a full millimeter too thick. Couldn't find a printable one that would fit my needs on Thingiverse so i've modelled one instead. The elongated holes make it possible to tweak the position slightly if your hotend doesn't fit the exact center of the groove. There's also a slight chamfer to the groove so slotting in the hotend should be easy even if the thickness isn't an exact match. Mine's printed in PET at 100% concentric fill, but anything should work, if your hotend's cold end is cooled properly.