Best way to create slot in 12 steel plate

Steel T-slot plate 7030 , ,77 € steel t slot plate Hardness for GG-25 gray cast iron made t-slotted floor plates is in the range of HB170-240 The surface flatness accuracy on the top surface of the t-slotted steel t slot track T-Slot Table Plate, T-slot, Tape, Threaded Rod, Tool Wrap, Trim Strip Color Black Plain Steel Silver Steel Unit of Measure inch mm

steel t slot plate Does anyone in Australia stock or supply T-slot plates? Steel or Al Or does everyone make their own? That seems a bit silly, but I can't find a local