Wasn't there some way to make it so that custom buildings were operated from outside the building itself, even unto the other sides of walls? I thought there was a Fences mod that used that effect somehow. If so, you might be able to make such a workshop that has a reaction that creates a vaporstone that boils to create the desired effects. You could place the workshop in your entrance hallway, operate it from the other side of one of the walls, and just have somebody run the reaction on repeat to make a constant cloud of vapor around the workshop while the operator was safely out of sight.
IIRC, the outside operation ability was doable because the workshop's actual dimensions and the xy coordinates of the square the workshop is operated from aren't actually required to be corrected, so for instance you could have a workshop that's 3x3 and operated from x=5 y=17 from the reference point (the upper-left corner IIRC). Since items that are created by a workshop are created in the workshop itself, this would work, but you'd need one custom shop for every possible distance you wanted it to be operated from, i.e. one for working from the west, one from the east, one from north, one from south, etc.