I made a custom bed assembly for my specific CoreXY printer. The printer is based on the very well-designed Vzbot 235/330, but I needed some specific dimensions to fit the aluminum extrusion frame I had and the oddly sized 340x250 bed.

The holes that connect to the aluminum extrusions use M5 bolts. The lead screw uses M3, and the linear bearing (LMK10UU) is screwed straight into the plastic with M4 bolts.

I have added the Fusion 360 file with the full assembly so you can check dimensions.