Nest Protect backplate - 70mm hole distance

I recently moved to a new place and my Nest Protect (battery) backplate didn't fit the holes in the ceiling box. As a learing project I tried to duplicate the original backplate, but with holes that fit my ceiling box (70mm between instead of 75mm).

If you need a different distance between the holes, use this link and change the 35mm line to what you need. https://a360.co/2TprzTC