Pretty much wondering if you can possibly add a feature to make product packages that use a base product but allows a user to add products in different categories.

In the admin section maybe a package editor that allows you to add categories of add-ons that are products that relate for upgrading.  This could be used for changing colors maybe even of a shirt or something no extra cost.  Or it could be an added amount of money or even take money away choosing different options in different categories.  

Being able to select from inventory with tracking of a product you may also sell individually.   Possibly a popup window for browsing product categories to find the product and select it to add to your package options. 

Not sure if I am being clear or if this is possible.  I have a few more feature requests I will make individual posts for.