Hypercube 300 / 400 Creality Bed Mount

These Z axis bed mounts are based upon a Creality 400mm heat bed. The holes are inset 35mm and the bed is 410x410 overall. For the frame, I used the calculations from http://superjamie.github.io/hypercube/ which gave me the following dimensions:

The heatbed I ordered is this one: https://www.ebay.com/itm/12V-180W-Creality-3mm-Aluminum-Thermal-Heated-Hot-Bed-Hotbed-For-3D-Printer-New/372091222016?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D44039%26meid%3Da94a8b8aa8d74b9ea12437c4a7