I think by now everyone has seen online ads for those clear, heat shrink
connectors that have a ring of low temperature solder in the center. You
stick both bare ends of the wire into the ends of the connectors and shrink
it with a torch. The heat shrinks the tubing and melts the solder more or
less simultaneously.

I ordered a small set to see if they actually worked or not. They did work
as advertised. I ordered a bunch more from Amazon, which is a better place
to buy them from.

<
https://www.amazon.com/dp/B07K81XGHP?aaxitk=wsdismF8LhUmy8igUy3pFw&pd_rd_i=B07K81XGHP&pf_rd_p=3fade48a-e699-4c96-bf08-bb772ac0e242&hsa_cr_id=5029917940301&sb-ci-n=asinImage&sb-ci-v=https%3A%2F%2Fimages-na.ssl-images-amazon.com%2Fimages%2FI%2F61E9jeL3SNL.jpg&sb-ci-a=B07K81XGHP>
for instance.

Jim