Calculator for Opencart

Good night.
It is necessary to develop a calculator of finished granite products for opencart

The https://disk.yandex.ru/i/2SUJfz2xqfD_Rg calculator itself

Set up a calculator
3, 5, 6... this is the thickness of the product, lower cost per m3 https://disk.yandex.ru/i/kzND0Q2X6TLilA
For example, a product of 100 * 50 * 8 will cost 10800p, because the volume is 0.04 * 270000p = 10800p
Exceptions https://disk.yandex.ru/i/XNUdMLVS5uU5wg