Loki has needed to give so many urine samples that he pees on command and doesn't even look at me funny when I stick the container under him

I use those disposable sandwich containers. For Sammy I've used a paper plate (with the waxy coating) and then dumped it into the container. If you can't get one, they can get one at the vet. Let the vet tech figure it out
Mine don't use pads but some people on here have suggested turning the pad over to the plastic side and then pouring it into a container.
GOOD LUCK