Hypercube Evolution extruder mount - square nut remix

I'm in the process of putting together a Hypercube Evo, but I'm attempting to do it without using heat-insert nuts.

There's remixes available of most of the parts required, but I couldn't find a suitable extruder mount - one design eliminated most of the heat-insert nuts but still required some to support the endstops, and several other designs don't design the nut slot 'ceilings' to be printed without supports, requiring supports to be placed inside the nut slots which is a pain in the ass t