DIY sub-kick
I'm sure you all know this but I thought there were a couple of good ideas in this clip:
https://www.youtube.com/watch?v=H6G2ZPBHEtg
https://www.youtube.com/watch?v=H6G2ZPBHEtg
https://www.turtlerockmastering.com/forums/
https://www.turtlerockmastering.com/forums/viewtopic.php?f=5&t=9056