Yes, liquid solder.  And someone did indeed try building a kit with it.  But was it conductive??  (Knight-kit one transistor radio.)
Details here:  <https://people.ohio.edu/postr/bapix/TranMidg.htm>

Rich KB8TAD



On Sat, May 20, 2023 at 8:26 AM Dennis Monticelli <dennis.monticelli@gmail.com> wrote:
Back when I was a teen there existed a real product called "Liquid Solder."  It came in a tube that contained a gray conducting glue.  

Dennis AE6C