These aren't anything to do with plastering either, but are about making things. They are two cabinets/stands for a couple of machies. On the left is a morticer, which drills square (and oblong) holes, and on the right is a band-saw which is a pretty flexible sawing machine. The cabinets are designed so the working tables of the machines are both at the same convenient height.
For those interested in details, the frame was built using those two machines to make the mortices and tennons; the housing slots for the panels were cut in the frame stanshions using a few passes on a circular saw table, the door frames were machines from old pieces of pine and rebated, with the mitres cut using a machine that makes picture frames, so giving razor sharp mitres. The tops are lipped with pine (using the mitring machine) and secured to the frame using pocket-holes. Finishing is three coats of a hard floor varnish.