On the space escalator, revised.

Both should work fine, (metal core or no core)

be that as it needs hollow points to insert the rods,

it's a small part of the cube so it will be solid,

but no metal core, would be much more cost effective.

Just that it needs higher interlocking indentations,
both to the sides and vertically, and finishing fusing
with liquid cement...

So I doubt it will be an issue of sustaining weight pressure
for both designs, rather, the cost of it, required to meet
the sheer scaled volume of it is the issue...
But if removing metal... Complete mineral.
Depending on raw resource access...