Customizable Magnetic Cargo Holder

This is a customizable version of the pictured (Fusion360) cargo braces. I inserted a flat piece of HVAC sheet metal under my cargo mat to attract the magnets. The magnets I used are [1.26" 90 lbs Neodymium Cup Magnet (Amazon)](https://www.amazon.com/gp/product/B01MFCWIU6), which have worked very well for my configuration.

Parameters (mm):

dim_x = Total x size
dim_y = Total y size
dim_z = Total z size
wall_thick = Thickness of side walls
base_thick = Thickness of base
cutout_y = Width of cutout. Set to zero if no cutout desired.
cutout_z = Height of cutout
mag_diameter = Diameter of magnets
mag_floor_thick = Thickness of surface below the magnet