Hypebox

This does not fit on an unmodified Ender 3. Need to extend the build area by 5mm in X direction, pysically and in your slicer.
Move your X endstop. It should still fit on a normal build plate, as those are 235x235.

Get yourself a 5 mm base plate. Cardboard, wood, you name it. I would not recommend printing one but you totally could.