If you do have items in your inventory to construct a blueprint that has upgradeable items you will be able to get free upgrades using it. To "benefit" from this setup the blueprint so that bots will begin to swarm (bigger distances makes this easier). If you upgrade ghosts which bots have already swarmed for they will construct the upgraded items despite you not having it in your inventory.
- Have Construction Drones in your inventory
- Have yellow belts in your inventory
- Place a ghost for some yellow belts some distance away
- See that bots swarm to construct those ghost
- Upgrade ghosts before bots arrive
If you do have items in your inventory to construct a blueprint that has upgradeable items you will be able to get free upgrades using it. To "benefit" from this setup the blueprint so that bots will begin to swarm (bigger distances makes this easier). If you upgrade ghosts which bots have already swarmed for they will construct the upgraded items despite you not having it in your inventory.