I did not know that..when i had tried dismantling the 15 tiles and reassembled them 15 -1 i was able to do it back.
Maybe this 7cube must be assembled first with all faces in same direction i.e. all blue top,orange down,red left,green right,yellow front,purple back.(or 1-6 if numbers)
But wonder if the position of blocks adjacent to vacancy is different if it is slided up or down in initial position.
this 3D rolling is new idea for me owing from your 8 cube. It is really interesting but somehow doubt if we are the first to tackle.
Looking like a 2x2 Rubik with a missing cube...
If we physically construct it the center mechanism must have a fix hold of all the 7 vertices.
when rolling it shall pivot without twisting the binder.. that is rigid construction.
Magnetic design involve magnetic strips on edges or center faces but + & - poles orientation is uncertain.
But Rubber band might work.., knot 4 cuts tightly ,make a small holes on vertices of hollow cardboard cubes
insert each rubber band end into the cube hole. A round bead as stopper will allow rolling without twisting..