The base mount will be supported by two of the holders. All of them are hold in place by M5 screws and hammer nuts.
Both holders need to be in place, before the bigger part, other wise the holder can not be screwed on your frame. Also put the holder model bottom to your print bed and only add support on the two positioning pins beside the screw hole.
The author remixed this model.
Added parts to mount the holder to a 3030 frame.