1+ on testing continuity.

Copper tape is not prohibitively expensive, for sure. It adds up when you do multiple guitars though. Most times I see copper tape on guitar building/repair sites in amounts just enough for one guitar.

By contrast a $5 role of HVAC tape (that I have in abundance living in Florida) is virtually a lifetime supply and I had a lot of it. I have not had oxidation issues with it. It tends to remain nice and shiny, and stuff that I have had on my garage door for years has remained conductive.

HVAC tape is also available everywhere here. If I run out, the big box store has plenty. However, I have never run out. I have two roles because I misplaced one of the roles.

Cheap and available means that I don't worry about messing it up. If something is not right, I can rip it out and do it again without worrying about reordering.

I have actually just ordered a small amount of copper tape, since it is great for curing any continuity issues. That said, I do like cheap and available, so I will probably keep using the HVAC tape too. It is not better in any intrinsic way than copper or paint to my knowledge, but it works.

Thanks for the rundown on the shielding paint. Was not aware of the issues with using it! That will be really useful. Thanks also for the ideas about conductivity enhancers. A staple is such a simple solution! Also, I was not aware that there was conductive adhesive.