ER-15 stock to AR-15 style stocks

I made this so that you can use an airsoft/real AR style stock with Ekcnheb's ER-15 model
I remixed this also of Mussys Buffer Tube & Castle Nut (AR-15, M-4, M-16) from https://www.thingiverse.com/thing:3210087 but I was not able to add this as a remix source and I would not like to not give them credit for their work, so I am putting it here.