This can be used for building any assembler product, including supermagnetic ring, that requires up to 3 inputs. Fewer inputs works okay too, as long as the output is listed as the 4th slot in the tower and the other inputs are in the top slots in the tower.
a 21x21 "plot" as described here: https://steamcommunity.com/sharedfiles/filedetails/?id=2389317246
This plot was inspired by this video: https://www.youtube.com/watch?v=rm0gK50GE3g
It takes 3 inputs, which must be the top 3 in the tower, and outputs 1 ouput.
CAVEATS: If you're using fewer than 3 inputs, make sure the output is still in the 4th or more slot from the top in the tower, or the tower will mistaken it for an input.