Gridfinity

Modeling for Gridfinity

Fusion360 plugin

There is a GrdifinityGenerator fusion360 plugin that will literally do all most all of the heavy lifting for you, simply pick wether you want magnets, holes, a label, and what dimensions you want, et voila.

Baseplates

My personal favorite baseplate is the magnet snap-fit baseplate from Gridfinity Magnet Light Baseplate.