Oldham coupler very simple but very (very) functional just a piece just a screw (M4x25mm, in my case) just a T_nut (M4, in my case) just one nut - blind nut or similar - (M4, in my case)

and last but not least: only a point of contact

NOTE: the distance between the trapezoidal screw and the 2040 profile is calibrated on my printer verify that the piece has the correct size and if necessary change the .stl