Voodoo: Thx. The site seems to have a problem with attachments at the moment, but will try again periodically.

Pyramid: Ditto the thx. I've downloaded it and started playing with it a bit. It's tempting to use it as a way to build all the mods into a single piece, but after my little experiment, it's clear I'm gonna have to upgrade my CAD skills a bit more.

What I tried was merging the x-carriage shelf from clough42's HE cooling solution for the hexagon into this x-carriage.

Clough42's model is in STL and SolidWorks..., and the X-carriage model is provided as STL and SCAD.

I imported both STL into FreeCAD and worked with that. Various details remained before I came to the conclusion that making the thing printable was gonna be a problem I didn't really want to mess with.

So..., in the interim, the upgrades are gonna happen using the MF x-carriage (which is what they're designed for anyway)..., and longer term, gonna put some time into learning OpenSCAD and then try something a little sexier.