Hi, i have different websites in developement, i use fancy and an other product designer.
i use fancy withe the pricing rules and the plus addon.
Fancy is the best for the integration on the pages but the other product designer give me some cool features.
For the size, the customer can upload an image, and change the size like in fancy, but on this addon the customer show the size and the price directly when he move the photo. Look the screenshot.
On this addon you can also add a pricing rule, who calcul the price by cm², it's really powerfull and save many time.
for example you say 1cm²=1.6€
the customer move the size from 10x10cm=100cm²=160€
It's really cool for sellers of car stickers, banners, frames, photography paper craft...and all the product who have for most important customisation the size
I hope tho show this thinks in the futures updates.