Version 1.0 Is fairly accurate model of the 40x40mm aluminum extrusions which the Creality Ender 3 uses. Could be the same for the CR10 and other models, unknown. It was made so that useful dimensions could be obtained for making things which fit into this v-rail properly. One could for instance, perform a boolean operation between this and another model to end up with a model which will fit into (or onto) the rail accurately. Small adjustments to the result may be necessary since this is a 1:1 scale model.
M20x20 and 20x40 v-rail models are also available.
It was designed completely in Blender v2.80 beta. As a beta version, support for the .blend file may break at any time; I'll try to update it with the stable version once that is released.