Railcore bed profile for your Slicer this works directly in S3D from the Railcore 300ZL Fusion 360 Cad file by Tony Akens.

This is an STL derived from Tony Akens Railcore II 300 ZL bed published in Fusion 360. This thing is used as an input model to Simplify 3d to enable viewing the build surface in your machine profile. The origin has been corrected to sit on the bed surface.