The best way to make urine is to drink a lot. Are you suggesting that you make up a pot of urine in your slow-cooker??
Why would you want to drink it??
Settle for beer: looks like urine, smells like urine, tastes like urine, and comes out as urine. Of course it is more expensive than your own urine, and drinking too much of it is not productive, except for making more urine.
Sorry, I don't think I answered your question, but I will be very interested in seeing if someone else does!!