4mm screw holes, 150mm inbetween the two arms, made for boards with 140mm trucks. Mounted with 2 drywall anchors and screws. Currently using it to hold my 40 inch drop-through with no problems. I recomend you place a level on the arms while mounting it to the wall to make sure you screw it into your wall horizontally.
Printed with the arms vertical, as long as you up the number of top and bottom layers, with atleast 4 walls, and an infill of atleast 40% this will be plenty strong to hold most boards printed in PLA. Suport is only needed from the build plate.