Need advice on shipping based on attributes

Can someone tell me how I might set this up?

I run a decal website and right now I am offering flat rate shipping on all products for $1.99 via USPS First Class Mail in standard large envelopes. Recently I started offering larger decals that do not fit in envelopes and I can not fold them so they must be shipped by USPS Priority Mail. Unfortunately, this costs me around $4 so I am having to eat the additional $2 in shipping the way I have it set up now.

What I'm looking for is a way to add the additonal $2 based on the size attribute that I have set up now. Anything larger than 12 inch should be charged $3.99 rather than $1.99. Is there an easy way to implement this?

As always, thanks....

You would really need to do a bit of custom coding to evaluate the shopping cart and detect how many products and their quantity have this attribute setting ...

Then the price could be adjusted ...

Note: this is a bit of a sticky peice of code, but it can be written ...

I just wrote a really nasty on where the shipping was based on a per product per attribute per 1st box per additional boxes per quantity that could fit per box on a per product per attribute level ... bases on dollar amount or percentage ... and sometimes free based on quantity ... with occasional minimum and maximum charges on a per product per attribute level shipping module ... :eek:

It is a totally nasty peice of code to handly all of those quirks to say the least ... and then configuring it for an admin interface really made it fun ... :lamo:

So in theory, what you are trying to do can be done ... and actually is 1000% easier than what I described as you just need to know how many products and their quanties are using what attributes based on a given options_id and options_values_id in the shopping cart ...

It would take a bit of coding but it can be done ... sounds easy eh? :blink:

Hahaha.. Yeah, sounds like a snap.

How about this. I don't ship by weight but perhaps I can use that instead. What I mean is that all the products are zero weight. Is it possible to add a weight to the size attributes of anything over 12 inch to +1 lb. Then could I use the ship by weight so that anything at less than 1 lb be shipped at $1.99 and anything above be shipped at $3.99? This would keep the appearance of flat rate shipping but oversized objects would be automatically adjusted. Additional smaller products or even multiple oversized products can still be shipped in the same package. I would like to still not display the weight on the invoice, checkout and shopping cart.

Does this sound like it has any merit?

Anyone? Would this work?

You'd need a better formula ...

Make sure that 1 * 7 qty would be 3.99 * 7 vs 0 * 7 quantity * 1.99 ...

But it could be done ...

Ajeh, thank you for your help, but I'm as dense as a block of wood. I don't follow what you're saying. I guess I need to read up on the ship by weight module.

What I'm thinking is that all products will have an initial weight of 0. Attributes for size greater than 12" would add a weight of 1 lb (this is possible right?). Then regardless of the number of items purchased the shipping of things less than one pound would be $1.99 and anthing greater would be $3.99 . Would I need to modify code to get this to work?