What you are looking for is DEPENDANT attributes - where the options offered in option "b" are dependant on what was previously selected in option "a".

Zencart 1.3.8 is unable to perform this feature.

There is a likelihood that it will be possible in ZC version 2 to build modules that are able to do this, but even then it will not be a "one size fits all" feature because of the "custom" nature of attributes in any given store.

Individual store owners wil still have to write custom code to effect this.

The only route you have is to apply what would otherwise be an attribute option, to the actual products - so in your case, individual products would have to be given a static characteristic of size, for example. Then, it's a case of needing only ONE variable attribute to adjust prices based on the painting's composition.

It would be hard work either way... even if attribute dependency was possible, because the data that relates to each individual product still needs to be input.