Enter the pickups you have available at the top of the tool, and the items that you're able to craft will appear at the bottom. You can double click on an item to view the recipes that are available, and click "Craft" to remove the pickups from your available pool. You can also click "Plan" to reversibly do the same; you can cancel and get the pickups back if you decide you don't like what's left after that craft.

If you think an item is useless enough, you can right click on it to blacklist it. You won't see it again unless you unblacklist it through the blacklist manager. You can also highlight certain items through the highlighter.

You can now link this tool directly to the game with this mod: https://steamcommunity.com/sharedfiles/filedetails/?id=2490374713

If you have the mod installed, pressing G while ingame will send all the pickups on the current floor to this tool, saving you the trouble of entering them manually.