I only did it once !
My pot now sits in a big old aluminum deep dish Pizza Pan ... it has shallow upturned sides , about 1" high but the pan will contain all the metal in the pot ...
which not only works to contain any leakages but when casting ... any splatters or spills now drop into the pan and not on my bench top ... this make Clean-Up a lot easier . Also gives me a place to put hot ladles , skimming spoons or hot moulds !
Mine is 16" diameter but it was in the kitchen cab and wife said to use it ...
a rectangular baking sheet with low sides would be just as good ... measure how much room you will need and buy a pan a few inches larger all the way around .
Gary