You can create a Custom List of any LEGO Parts. They can be added by importing from an external website such as a BrickLink order, or directly from a file such as CSV or LXF files etc.
The Custom List can then be Built as if it was a Set or MOC by clicking thebutton.
The Build Engine will find out what parts in the list you do and don't have according to your LEGO Collection. This will take you to the Build Results page as per Building a LEGO Set/MOC where you can modify the settings and find your missing parts.