Any tech component design that has a '0' mineral cost in some category, e.g.
Active Sensor Strength: 16 Sensitivity Modifier: 80%
Sensor Size: 1 HS Sensor HTK: 1
Resolution: 100 Maximum Range vs 5000 ton object (or larger): 12,800,000 km
Range vs 1000 ton object: 512,000 km
Range vs 250 ton object: 32,000 km
Chance of destruction by electronic damage: 100%
Cost: 16 Crew: 2
Materials Required: 0x Duranium 16x Uridium
Development Cost for Project: 160RP
Will get a non-zero cost for that mineral if you switch to a tech component that uses that mineral, e.g.
Max Ship Size: 6000 (300000 tons) Max Squadron Size: 3 Max Jump Radius: 50
Jump Engine Size: 1000 HS Efficiency: 6 Jump Engine HTK: 200
Cost: 62797 Crew: 2000
Materials Required: 12559.4x Duranium 50237.6x Sorium
Development Cost for Project: 627970RP
Resulting in this if you switch back to designing the first component:
Active Sensor Strength: 16 Sensitivity Modifier: 80%
Sensor Size: 1 HS Sensor HTK: 1
Resolution: 100 Maximum Range vs 5000 ton object (or larger): 12,800,000 km
Range vs 1000 ton object: 512,000 km
Range vs 250 ton object: 32,000 km
Chance of destruction by electronic damage: 100%
Cost: 16 Crew: 2
Materials Required: 12559.4x Duranium 16x Uridium
Development Cost for Project: 160RP
This can result in wasted minerals if the player doesn't notice, depending on severity. Also happens with to ship engines, tritanium and missile engines, etc.
I remember a variant involving uridium and missiles with no sensors that emptied a stockpile. Maybe there's also one with tritanium and missiles with no warhead, but I'm less sure on how to reproduce the missile design bugs.
Closing aurora resets stuff to zero as a workaround, so I keep forgetting to report this.