I did some research on the Tube Zipper, I was looking at envelope filters and was intrigued by the fact that the envelope follower on Tube Zipper was so novel the designer was actually able to secure a patent for it, which is very uncommon in the world of guitar/bass pedals. The patent was withdrawn by the designer a while back so it's usable if I wanted to make something with it, but I spun a prototype of it and I wasn't in love with it.
So I did what I often do when I make something that I'm not that excited about:
I moved it into a DIY project, set to be released next month

I've affectionately called it "Sweater Vest".
Furthermore is chugging along. I'm thinking 2024 is the year it gets finished.