You cannot use MDF in snake vivs unless it is treated/covered because it is very toxic
It's made of wood dust, which is compacted and glued together. it's the glue dust that's toxic given off when the wood is cut, it can form cancer if inhaled.
I'd advise against it, if you cut holes in MDF make sure you fully ventilate the area and give it a few days to stand in again a well ventaliated area.