I took one apart to see how feasible it would be to do an open roof/enclosed side rack.
They come apart relatively easily. The end doors are a press fit and come right off. The roof is lightly glued on but it comes off easily with a little gentle prying. The side panels are etched as one whole piece, not individual panels. The vertical uprights that you see from the outside (not including the solid end panels by the ladders) are actually part of the etched side piece. Red Caboose masks the side panels and paints the uprights the car color. This etched piece is press fit into grooves in the flatcar deck and comes off easily. The second deck and interior (non-scale) vertical uprights look to be molded as one piece which appears to be glued securely to the flatcar deck with the ladders and door guides added on. I didn't try to take it off so I don't know how hard it is to get off.
So yes, they can be taken apart, but painting is going to require masking the side panels, and figuring out how to remove the upper deck from the flatcar. Also, once you "break the seal" of the glued-on roof, it really needs to be glued back on as it does not snap into place, and the doors will not snap on securely if the roof is loose.
Pete D.