Bigger bracket to attach your 20mm extrusion to table and support Z-axis to stay in 90° angle and stabilizing Z-axis.
Holes are designed for M4 screws with 10mm OD washers.
Can be printed with 200x200 mm bed, barely. Make sure your bed alignment is correct as the print size is very close to 200x200 mm.
Added another version with sideways support for even more rigidity. This version needs some supports to print.