Calculator on product page VM3

[2dmaster]

Hign importancy. Help to make pls, or help to question witv vm.

How to make the card the entered value of the goods? type calculator ....

from product text box, for example, "enter the number of meters"

i`m using csvi pro + custm fiels, ajax minicart, and mcf_filter

  twat

[PRO]

??

http://extensions.virtuemart.net/products/custom-size-detail