I have shells that I have wanted to add elastic to, to make the neckline tznua without the need for a safety pin. I may have time during the 9 days and want to know if it is permissible to sew elastic into the neckline during this time. Thank you
It is permitted during the nine days. Although we don’t sew during the nine days, however small repairs, such as fixing a button, or the hem of a dress etc. are permitted. Adding the elastic would be comparable to fixing a hem.
Kaf Hachaim 551-107, Rivivos Efrayim 5-376(11), Orchos Rabeinu 2 pg. 129, Mbais Levi pg. 26, Kovetz Halachos (Bein Hamitzarim) 13-2, Poskim.