Submerge in cold water.
Set the hob to the lowest setting and it will take an hour to reach the boil, then boil for a further hour or more.
Place a weight on top of it to squeeze out the excess liquid and also to ensure that it is flat at both ends.
Place on a plate and stick into the fridge.
When it is cool slice it.
Observe my new ceramic knife. This is literally razor sharp. I usually end up cutting myself.
I am thinking of taking one in my hand luggage on the plane, do you think that would be a good experiment to test their scanners?