I already set up my mule as the receiver for the items, i just need to know how to make my bot keep certain mats in the bags instead of selling them. Thank you.
Well why don't you give us some information instead of dangling a carrot?
1.) Botbase?
2.) Profile or an indication of profile scope?
For a start I recommend ItemRemover2, it will allow you to set a protected list there (you can edit the settings via text files for easy copy paste) once the plugin has initialised.
Without any more information we'd be wasting our time guessing for you.