NOT electrical tape. I think first aid tape would be excellent - probably about as good as proper rim tape. Duck tape, well, maybe. In a pinch, for a while. The better grades like gaffer tape or Gorilla tape are probably good. The cheap stuff is garbage. If you live up north and have hockey tape, that'd be perfect.

I'd get them out of there ASAP though - the adhesive turns to gooey soup in a few weeks, especially if they get wet.

Electrical tape will probably work OK if your pressures are not too high (say < 50 PSI).

For that matter, at low pressures the cheap bikes use a rubber strip - if you have an old tube you could use that.