I going to run 1/2" EMT conduit on the bottom of a joist. The standard straps I have are too wide to get both nails/screws in. I would prefer to run the conduit down the center of the joist. I wouldn't be able to do this with a single nail/screw strap. I was thinking of using a thick metal tape with holes every inch or so in it. I have some holding up my gas line. Do they still make it? If so, what is it called? Or could I used plastic zip lock ties instead?
It is called perforated strapping and it comes in steel or a plastic material. That would be OK to use.
I hate these but they're what you asked for.
EMT Drive Strap
What about something like this Conduit Hanger