I identified the manufacturer from the flange face. Now, comes the task of finding a resource with enough throw-away stock because they use enough arts and crafts paper
This plug is made by Badger Plug, Greenville, Wisconsin. Made of HDPE, item # 123P21. Patent 5,351,825
(gee, cut and paste is so easy
Porcupine - these aren't the same KIND of plastic cones !
(leave it to you....
Juro - just had this thought: what about roughing the blind side and it's attendant position in the wash basin, then 5200ing them in, instead of some other type of cement.