If the gadget isn't working, check if it requires FE (Forge Energy) or a similar power source. You may need a Battery or Power Cell to charge it.
If this is a specific numbered challenge from a curriculum (like a CTF or a programming lab): 18_its_just_a_gadget
Safely deletes large areas of blocks. Note that it does not drop the items; they are simply voided. If the gadget isn't working, check if it
Press the G key (default) to open the GUI. Here you can change modes (e.g., Build to Me, Vertical Column, Horizontal Wall). Note that it does not drop the items; they are simply voided
Determine if the gadget can be "tricked" into a state it wasn't designed for (e.g., skipping a security check).
Check if the gadget accepts parameters it shouldn't.
If you are referring to the popular "Building Gadgets" mod (often part of larger quest packs), this topic usually covers the automation of complex structures.