What do we call this adjustable platform used to ensure that something is positioned strictly level in a lab?  should be put on top of this platform, after which the platform is adjusted "using a level". The text describes a vertical SDS-PAGE procedure. I wonder what such benchtop lab platforms are called. In my Russian text it is called "заливочный столик" (pouring table, casting table).

I remember using those for agarose gels as an undergraduate, though using them for PAGE doesn't make a lot of sense unless your bench is seriously out of level. Anyways, they can be called levelling tables and are used to promote uniform migration across the gel. Casting table also seems reasonable.