They could conceivably order a 2.5 mm thick base and then grind that down to fit with the edges .
It would still result in a 1.8 mm thick base and there would be no reason to go about doing that .
They could conceivably order a 2.5 mm thick base and then grind that down to fit with the edges , but it would still result in a 1.8 mm thick base and there would be no reason to go about doing that .