Easiest way to build a horizontal hotend mount at home, without printing
You could cut a v-notch groove in a piece of plywood to hold one side of the groovemount neck, and then use a bolt through another piece of wood to push the neck into the V-notch. 

There are lots of options when building RepStraps and JunkStraps. Really depends on what sort of hardware and fabrication capabilities you have on hand.