When it comes to building the models I'm using Bricklink. I find it a bit cumbersome to have to make my model public to get the Inventory XML, but of course that works somehow. It would be nice to have that button in the personal library, too.
But what would be even better would be a context sensitive XML export directly in the workshop! I would have shown a scribble, but forum functionality is pretty limited 😃
When you select multiple parts, those are shown on the right "object" panel below "children".
In the same window there could be "Inventory" right after "Point", "Children", "Parent".
2 Buttons within:

• "Copy Bricklink XML" -> copies the XML to the clipboard (no download needed as this can be pasted perfectly in the bricklink upload form)
• "Show unsupported parts"-> different ways possible to make life easier 😃 1) opens a new window with a short table: picture, part no, name, color, amount 2) same table but copied to clipboard in text form 3) mark those parts in the workshop (the user could do with them whatever he wants: group them for overview to get them manually into bricklink wanted lists, move them out the model to see which parts are unsupported)

By using an export based on selected parts, I could:

• have a faster interaction with bricklink to decide on specific usage of parts based on their availability and prices
• create wanted lists with sub-models (e.g.: having designed a complete train I could split wanted lists into different coaches)
• streamline process of designing and creating with real bricks